**Process Specification for the Manual Arc Welding of Aluminum Alloy
Hardware**

+-----------------------------------------------------------------------+
| **Engineering Directorate**                                           |
|                                                                       |
| **Structural Engineering Division**                                   |
|                                                                       |
| **November 2007**                                                     |
|                                                                       |
| ![](media/image1.png){width="1.4027777777777777in"                    |
| height="1.1534722222222222in"}                                        |
|                                                                       |
| National Aeronautics and                                              |
|                                                                       |
| Space Administration                                                  |
|                                                                       |
| **Lyndon B. Johnson Space Center**                                    |
|                                                                       |
| Houston, Texas                                                        |
+-----------------------------------------------------------------------+

**Process Specification for the Manual Arc Welding of Aluminum Alloy
Hardware**

+------------------+---------------------------------+------+---------+
| **Prepared by    |                                 |      |         |
| :**              |                                 |      |         |
+------------------+---------------------------------+------+---------+
|                  | Daniel J. Rybicki               |      | Date    |
|                  |                                 |      |         |
|                  | Materials and Processes         |      |         |
|                  | Branch/ES4                      |      |         |
+------------------+---------------------------------+------+---------+

+------------------+---------------------------------+------+---------+
| **Reviewed by    |                                 |      |         |
| :**              |                                 |      |         |
+------------------+---------------------------------+------+---------+
|                  | Lucie B. Johannes               |      | Date    |
|                  |                                 |      |         |
|                  | Materials and Processes         |      |         |
|                  | Branch/ES4                      |      |         |
+------------------+---------------------------------+------+---------+

+------------------+---------------------------------+------+---------+
| **Approved by:** |                                 |      |         |
+------------------+---------------------------------+------+---------+
|                  | Bradley S. Files, Chief         |      | Date    |
|                  |                                 |      |         |
|                  | Materials and Processes         |      |         |
|                  | Branch/ES4                      |      |         |
+------------------+---------------------------------+------+---------+

  ----------- --------------------------------------------- ---------------
  REVISIONS                                                 

  VERSION     DESCRIPTION                                   DATE

  \--         Original version                              4/6/95

  A           Formatting, elimination of subclasses and     4/20/98
              types, refers to ASTM specs E1417 and E1742,  
              refers to heat treat PRC-2002.                

  B           Formatting, changed process owner, rewrite    07/07/99
              numerous sections for clarification, deleted  
              requirement for WIR, deleted section 8.2 on   
              audits, added section 8.3 on WPQ, deleted mil 
              specs for NDE, added PRCs for NDE.            

  C           Comprehensive technical rewrite modeled from  03/07/03
              changes made to PRC-0005, Revision C. Added   
              reference to JPG 5322.1 and details for       
              welding of precision cleaned hardware         
              (Reference memo ES-01-027).                   

  D           Comprehensive rewrite to combine PRC-0001 and 02/10/2004
              PRC-0003 and make editorial changes. PRC-0003 
              will be cancelled with this change. Make      
              provision for Class D welds for ground based  
              hardware.                                     

  E           Added Class D criteria to section 7.1.        03/18/2004
              Modified "General" section in Appendix A.     

  F           Removed "Technology" from preparer's and      03/20/2006
              approver's branch name and changed approver   
              name to current Branch Chief name (i.e.,      
              Hernandez to Files).                          

  G           Add reference to Class D welding in 3.0 for   11/21/2007
              on-site JSC work authorized by the JSC        
              Engineering Directorate's manufacturing       
              operations. Add additional Class D            
              stipulations in last paragraph of 3.1. Added  
              Reviewer signature block.                     
  ----------- --------------------------------------------- ---------------

#  **1.0 SCOPE**

This process specification provides the minimum requirements that govern
the manual arc welding of aluminum alloy hardware. Design, procedural
and quality assurance requirements are given. All work instructions and
Weld Procedure Specifications (WPS) used during welding shall satisfy
the requirements of this process specification.

# **2.0 APPLICABILITY**

This process specification applies to manual (and semi-automatic) arc
welding of aluminum alloy hardware that is fabricated under the
authority of NASA/Johnson Space Center (JSC) by any of the following
types of welding processes and any of their process derivatives (e.g.,
pulsed current, etc.):

a\. Gas tungsten arc welding (GTAW).

b\. Gas metal arc welding (GMAW).

c.  Plasma arc welding (PAW).

d.  Soft Plasma arc welding (SPAW).

The term "flight hardware" refers to any hardware used as a part of a
spacecraft, aircraft, or payload. The term "ground based hardware"
refers to any hardware made for facilities (buildings and related
accessories), ground support equipment, training and mockup mission
equipment, engineering prototype and development hardware, and test
equipment.

Future builds of hardware where the existing engineering documentation
calls out NASA/JSC PRC-0003 for welding shall utilize this
specification. Existing hardware fabricated to PRC-0003 requirements
shall not be affected by this change. In addition, existing engineering
documentation that specifies welding per PRC-0007 shall be accommodated
by PRC-0001, Class D. Existing hardware fabricated to PRC-0007
requirements shall not be affected by this change.

# **3.0 USAGE**

This process specification shall be called out on the engineering
drawing by a drawing note with the following general format which
specifies the PRC and weld class nomenclature:

**WELD AND INSPECT PER NASA/JSC PRC-0001, CLASS X.**

Regarding onsite JSC work for minor facilities repair and manufacture of
shop aids that is performed under the work authorization of the JSC
Engineering Directorate\'s manufacturing operations, welds shall be
considered Class D, if they conform to the Class D weld criteria and
exclusions herein. Execution of these welds shall not require the
formality of an engineering drawing, and may be executed by verbal
orders.

To minimize fabrication costs by avoiding over-inspection and
unnecessary rework/repair, individual welds, or components on a weldment
shall be classified separate where possible. This can be accomplished by
including a note on the engineering drawing with the general format
shown below which specifies only the PRC nomenclature. The weld class
shall then be indicated by either: 1) calling out the specific weld
class with the welding symbol at the individual weld joints or, 2) by
using specific flag notes with the welding symbol at the individual weld
joints. Refer to Figure 3.0a and 3.0b below for examples of these
methods.

WELD AND INSPECT PER NASA/JSC PRC-0001. WELD CLASSES SHALL BE AS
INDICATED AT WELD LOCATION CALLOUTS.

## 

## 

## 

## 

## 

## 

## 

## 

## **3.1 WELD CLASSIFICATION**

Welds made using this specification shall be primarily classified in
accordance with the service conditions of the weldment. Therefore, the
\"Class\" defines the severity of service intended for the joint by
design and governs the extent to which quality assurance provisions are
applied to the weld joint as specified herein.

Alternatively, individual welds, welded connections, or entire weldments
(for simplicity, the terms weld, welded connection, and weldment will be
used interchangably) may be classified by relating the weld to the
factor of safety used in the design. However, when classifying welds in
this manner, regardless of the factor of safety, adequate consideration
should be given to the severity of the service conditions (e.g., static
loading vs. dynamic loading, cyclic, vibration, fatigue, corrosive,
extreme temp, etc.), material characteristics (e.g., ductility,
toughness, etc.), and the potential consequences of weld failure.

Where conditions exist that make it difficult to choose between 2 weld
classes, then the more stringent of the 2 classes shall be applied.

Quality assurance provisions for all weld classes are detailed in
Section 7.0. Weld classes shall be chosen on the basis of the following
definitions:

a.  [Class A]{.underline} (Flight or non flight) --- Applies to welds in
    critical load bearing elements that are not fail-safe. Class A welds
    are typically used in primary load bearing connections. Failure of a
    Class A weld in service would be catastrophic and would result in
    the loss of life, system(s), control, or major components.
    Alternatively, if it is determined from appropriate engineering
    analyses that a weld has a Factor of Safety (FSuts) vs ultimate
    tensile strength of the calculated minimum weld throat cross section
    of \<2.0, it shall be designated as a Class A weld.

b.  [Class B]{.underline} (Flight or non flight) --- Applies to welds in
    load bearing elements that are fail-safe. Class B welds are
    typically used in secondary load bearing (i.e., shared load)
    connections. Failure of a Class B weld in service would reduce the
    overall efficiency of the system, but the loss of the system(s) or
    endangerment to personnel would not be expected. Alternatively, if
    it is determined from appropriate engineering analyses that a weld
    will have a FSuts of ≥2.0 and \<3.5, it may be designated as a Class
    B weld.

c.  [Class C]{.underline} (Flight or non flight) --- Applies to welds
    that are in minor load bearing elements that are fully contained
    where failure in service would have minor or no affect on the
    efficiency of a system and endangerment to personnel would not
    occur. Class C welds are typically used in secondary or tertiary
    load bearing (i.e., shared load) connections. Alternatively, if it
    is determined from appropriate engineering analyses that a weld will
    have a FSuts of ≥3.5 and \<5.0, it may be designated as a Class C
    weld.

d.  [Class D]{.underline} (Non flight hardware only) --- Applies to
    welds that are in noncritical elements and where failure would have
    no affect on the efficiency of a system and endangerment to
    personnel would not occur. Class D welds are typically used in
    connections where any expected load transfer at the weld would be
    negligible. Alternatively, if it is determined from appropriate
    engineering analyses that a weld will have a FSuts of ≥5.0, it may
    be designated as a Class D weld. In any case, Class D shall not be
    specified for welds used for making connections onto critical or
    primary load path elements (e.g., lift points, etc.) or elements
    directly related to personnel supporting activities, regardless of
    the loading condition/direction.

In addition to the above definitions, the following requirements shall
also apply to weld classifications:

-   If any weld intersects or overlaps another weld of a higher
    classification, then the lower classed weld shall be automatically
    upgraded to the higher of the 2 weld classes and subjected to the
    appropriate quality assurance provisions.

-   If any weld falls within ½" of any higher classed weld, then it
    shall be automatically upgraded to the higher of the 2 weld classes
    and subjected to the appropriate quality assurance provisions.

-   Class D welds are only intended for on-site (JSC) fabrication
    operations. All welds that are specified as Class D on weldments
    that are subcontracted off-site shall be recognized as Class C and
    shall be subject to all applicable Class C requirements specified
    herein. Class D welds shall only apply to welds made on 1000, 3000,
    5000 and 6000 series aluminum alloys. In addition, welds joining 2
    or more dissimilar base metals shall not be allowable under Class D
    provisions.

## **3.2 WORK INSTRUCTIONS**

Work instructions shall be generated for implementing this process
specification. The work instructions shall contain sufficient detail to
ensure that the manufacturing process produces consistent, repeatable
results that comply with this specification. At JSC, these work
instructions are approved as Detailed Process Instructions (DPIs) that
describe in a detailed, step-by-step format the required procedures,
equipment, and materials to be used for conducting a given process. If
this manufacturing process is to be performed by an outside vendor, work
instruction development shall be the responsibility of the vendor.

## 

## **3.3 DESIGN REQUIREMENTS**

a.  The design of welded joints (including weld sizes) shall utilize
    adequate engineering analysis methods (e.g., stress analysis,
    fracture mechanics/fracture control, FEA, FMEA, etc.) to ensure that
    the resultant connection strength is capable of successfully
    transferring the maximum load expected to pass between the
    interconnecting members and meet the required factors of safety and
    design margins.

b.  All engineering drawings shall depict welded joints using the
    applicable symbols described in AWS A2.4.

c.  The engineering drawing shall specify any additional or alternate
    testing or inspection requirements. Where spot, intermittent, or
    other special inspection requirements are specified that deviate
    from those stated herein, it shall be detailed on the drawing as a
    note or by using the applicable symbology described in AWS A2.4. For
    Class A welds, alternate or reduced NDE requirements shall not be
    allowed.

d.  All alloys with magnesium levels \>3.0% Mg, including filler alloys,
    shall not be specified for service conditions exceeding 65°C
    (150°F).

e.  Class A welds are expected to be welds requiring full strength of
    the weld joint therefore, these welds shall be a groove design and
    full penetration wherever possible. The ability to successfully
    perform radiographic examination on these weld joints shall be
    considered during design.

f.  Unless otherwise specified on the engineering drawing, hardware will
    be delivered in the "as welded" condition. If required, the
    engineering drawing shall include notation that will specify the
    appropriate heat treatment process, referencing NASA/JSC PRC-2002.

g.  Intermittent welding (skip welds) shall not be specified for Class A
    joints.

h.  Intermittent welds shall not be specified for butt welds (square or
    groove design) unless the unwelded portions of the joint are
    adequately supported to prevent one member from coming out plane
    with the adjoining member.

i.  Weld filler material shall be specified on the engineering drawing
    in the parts list.

# **4.0 REFERENCES**

The standards listed below shall be considered a part of this
specification to the extent specified herein. Unless otherwise
indicated, the revision that is in effect on the date of invitation for
bids or the date of request for proposals shall apply.

**a. American Society of Nondestructive Testing (ASNT)**

SNT-TC-1A *Personnel Qualification and Certification in Nondestructive
Testing*

**b. American Welding Society (AWS) Standards**

ANSI/AWS A2.4 *Standard Symbols for Welding, Brazing and Nondestructive
Testing*

ANSI/AWS A3.0 *Standard Welding Terms and Definitions*

ANSI/AWS A5.10 *Specification for Bare Aluminum and Aluminum Alloy
Welding Electrodes and Rods*

ANSI/AWS A5.12 *Specification for Tungsten Arc Welding Electrodes*

ANSI/AWS B2.1 *Standard for Welding Procedure and Performance
Qualification*

ANSI/AWS D1.2 *Structural Welding Code - Aluminum*

ANSI/AWS QC-1 *Standard for AWS Certification of Welding Inspectors*

**c. Compressed Gas Association, Inc.**

G-11.1 *Argon, Commodity Specification for*

**d. Federal Documents**

BB-H-1168 *Helium Federal Specification*

**e. Military Documents**

MIL-A-18455 *Argon, Technical*

MIL-P-27407 *Propellant Pressurizing Agent, Helium*

# **f. NASA/JSC Documents**

JPG 5322.1 *Contamination Control Requirements Manual*

PRC-0008 *Process Specification for the Qualification of Manual Arc
Welders*

PRC-2002 *Process Specification for the Heat Treatment of Aluminum
Alloys*

PRC-6503 *Process Specification for Radiographic Inspection*

PRC-6504 *Process Specification for the Ultrasonic Inspection of Wrought
Metals*

PRC-6505 *Process Specification for Magnetic Particle Inspection*

PRC-6506 *Process Specification for Liquid Penetrant Inspection*

SOP-004.5 *Control of Weld Filler Materials, Electrodes, and Fluxing
Materials*

SOP-007.1 *Preparation and Revision of Process Specifications*

TI-0000-04 *Training Instruction for the Welding Processes*

**g. NASA Headquarters**

NASA-SPEC-5006 *General Fusion Welding Requirements for Aerospace
Materials Used in Flight Hardware*

## **5.0 [MATERIAL REQUIREMENTS]{.underline}**

All base materials used in the welding of hardware per this
specification, shall meet the requirements of an applicable JSC material
specification unless otherwise specified. If a JSC material
specification is not available, then an applicable commercial
specification or a manufacturer\'s specification shall be used. Filler
and electrode materials used shall conform to the applicable AWS
specification listed herein. Filler metals and electrodes purchased to
alternate specifications shall be allowed provided they meet the minimum
requirements of the specifications listed herein.

### 

### **5.1 SHIELDING AND PURGE GASES**

Allowable shielding gases (including purge gases) are listed in Table I.
Gases purchased to alternate specifications shall be allowed provided
they meet the minimum requirements of the specifications listed herein.
Mixtures of these gases are allowed and the nominal mixture used for the
qualification welding shall be that used for production and shall be
listed on the WPS. All shielding and purging gases and nominal gas
mixtures shall be treated as an essential procedure qualification
variable and shall be subject to the AWS B2.1 requirement for these
variables. In addition:

a.  All gases used for welding shall be delivered through clean
    low-nonvolatile residue (NVR)/particulate tubing.

b.  Nitrogen or hydrogen gas in any concentration, shall not be used for
    shielding or purging in any welding operation governed under this
    specification.

c.  All gases used for shielding or purging shall have a dewpoint of
    -40°F (minus 40 °C) or better.

**Table I. Allowable Shielding Gases**

  ------------------- --------------------------- -----------------------
  **Gas**             **Description**             **Specification**

  Argon               Gas                         MIL-A-18455

  Argon               Type II, Grade B            CGA G-11.1
                      (Liquefied)                 

  Helium              Type I, Grade A             MIL-P-27407

  Helium              Grade A                     BB-H-1168
  ------------------- --------------------------- -----------------------

### **5.2 FILLER METALS AND ELECTRODES**

Filler metals shall be selected from Table II. Alternate selections may
be warranted based on specific service conditions, design requirements,
or other factors however, the alternate selection shall be approved by
the NASA/JSC M&P organization prior to use. In addition, the following
shall apply:

a)  Non consumable tungsten and tungsten alloy electrodes for GTAW and
    PAW shall be selected according to the process being used at the
    direction of the responsible M&P organization. The electrode type
    and size shall be specified on the WPS.

b)  Weld filler metals shall be called out on the engineering drawing in
    the parts list.

**5.2.1 [Control and Storage]{.underline}**

Welding electrodes shall be stored in a clean, dry, and controlled area
that provides protection from contamination, physical damage, and
commingling of alloys. Any form of electrodes or weld filler metal which
is damaged, dirty, exhibits oxidation/corrosion or has been contaminated
with water, oil, grease or any form of hydrocarbons shall not be used
and shall be disposed of in accordance with an appropriate disposal
procedure. For JSC operations, welding electrodes and filler materials
shall be controlled in accordance with SOP-004.5. Outside vendors shall
provide control and storage according to the applicable material
specification or manufacturer\'s recommendation, whichever is more
rigid.

######### **Table II. Weld Metal Fillers For Aluminum and Aluminum Alloy Combinations**

  ---------- ---------- ---------- ---------- ---------- ---------- ---------- ----------
  **BASE     **2014**   **2219**   **5052**   **5083**   **5086**   **5456**   **6061**
  METAL**                                                                      

  **2014**   **2319**   **2319**                                               **4145**

  **2219**              **2319**                                               **4043**

  **5052**                         **5654**   **5356**   **5356**   **5356**   

  **5083**                                    **5183**   **5356**   **5183**   

  **5086**                                               **5356**   **5556**   

  **5456**                                                          **5556**   

  **6061**                                                                     **4043**
  ---------- ---------- ---------- ---------- ---------- ---------- ---------- ----------

# **6.0 PROCESS REQUIREMENTS**

All weldments shall be fabricated according to the requirements of this
process specification and shall be performed using Welding Procedure
Specifications (WPS) that have been qualified in accordance with the
requirements of Section 8.0 in addition to that as detailed below.

## **REQUIREMENTS FOR ALL PROCESSES**

6.  **[Preweld Cleaning of Weld Joint Surfaces]{.underline}**

Prior to welding, all weld joint surfaces within a minimum of ½" of the
weld line shall be cleaned in a manner shown to be adequate and
repeatable in producing a surface cleanliness level conducive to
producing sound welds by a given weld process. The specific process and
procedural steps to carry out the process shall be part of the procedure
qualification activities and shall be appropriately detailed on the
qualification and procedure specification (PQR and WPS) documentation as
well in the production work instructions. Welder's shall be trained in
these same methods and process techniques.

2.  [**Intermittent Welding**]{.underline}

Applicable to all processes, weld joints that are specified for
intermittent welding shall have the ends of the parts, or departure from
a straight weld line (e.g., square corner, etc.), welded regardless of
the interval of the weld.

3.  **[Tooling and Fixturing]{.underline}**

Weldments shall be fixtured with appropriate tooling as deemed necessary
by the fabricator. Tools and fixtures shall be constructed of materials
that will not interefere with the welding process nor damage or
contaminate the hardware.

4.  **[Temporary or Tack Welding]{.underline}**

Temporary (includes the term "tack" welding) welding in areas of the
hardware not planned for welding or where the temporary weld will not be
totally consumed by the final weld, shall not be allowed. All temporary
welds placed at or in a weld joint shall be ground and feathered
appropriately to accommodate the final welding process to achieve the
expected deposit of sound weld metal. All temporary and tack welding
shall only be performed by a welder(s) whose qualifications are current
and applicable.

5.  **[Welding Equipment]{.underline}**

Equipment (e.g., power supplies, positioners, flowmeters, etc.) used for
manual welding operations need not have calibrated instrumentation
(dials, gauges, indicators, meters, etc.). However, reference indicating
instrumentation (e.g., dials, meters, gauges, etc.) shall be fully
functional (useful output) and in good working order. The equipment
shall be capable of being used by a qualified welder, using a qualified
procedure, to produce sound welds.

1.  **[Welding Precision Cleaned Hardware (including tube preparation
    for welding)]{.underline}**

Whenever precision-cleaned hardware must be maintained clean during
welding into an assembly, the welding operation shall be performed in a
dedicated Class 100,000 Clean Work Area. This may require temporary
tents over the weld area and/or local monitors located in the area of
welding to ensure the Class 100,000 environment is being met. Portable
particle counters shall be located as close as possible to the work
area, so as to monitor local contaminants during tube preparation and
welding. Tools used in weld preparation and welding (such as cutter,
weld head, files) shall be visibly cleaned per JPG 5322.1 and maintained
clean (e.g. bagged when not in use).

For hardware that cannot be subsequently precision-cleaned, a proven
method for protecting against system contamination during tube
preparation and welding shall be implemented. One such method is the use
of a physical barrier, such as plugs. The installation and removal of
plugs shall be tracked by a reliable method and independently verified.
Prior to plug removal, the exposed internal surfaces of the tube shall
be cleaned using a swab wetted with an approved solvent, and positive
backpressure shall be maintained as the plug is removed.

Tube cutters shall use a sharp blade, changed frequently. Cutting shall
be performed with minimal cutter pressure to aid in preventing particle
generation. Vacuum shall be used during tube facing operations to remove
particulate. Whenever possible, facing operations shall be performed
away from the weld assembly area, to reduce particulate contamination of
the welding work area. Tube facing shall be performed without the use of
cutting oils, other fluids, lubricants or coolants. Abrasives, including
sandpaper or abrasive pads, shall not be used inside tubes or when
unprotected internal surfaces are exposed. After each tube preparation,
and prior to welding, a high-velocity gas purge shall be performed. The
purge gas velocity shall be the maximum attainable using a 90-psig
source. The purge gas used during facing and welding shall meet the
hydrocarbon and particulate requirements for the system under assembly.
The purge gas shall be supplied in accordance with Section 5.1.

**6.2 PROCESS SPECIFIC REQUIREMENTS**

### 

### **6.2.1 Gas Tungsten Arc Welding**

Additional filler metal shall be used with the GTAW process unless it
can be demonstrated by weld qualification that weld cracking and other
undesirable metallurgical conditions will not exist in the finished weld
made without filler metal (autogenous weld). This method of welding
shall be specified on an approved WPS.

### **6.2.2 Gas Metal Arc Welding**

The GMAW short circuiting transfer mode shall not be used to fabricate
flight hardware nor to join materials of greater than ¼" thickness
unless specifically qualified and documented in a WPS. Thickness
limitations for this process mode shall be as specified by AWS B2.1. The
process can be used to deposit the root and additional passes in the
root region of butt joints exceeding that specifically qualified for, up
to a deposited weld metal thickness as allowed by the WPS. The GMAW
short circuiting transfer mode shall not be used to make Class A welds
designated for any type of hardware.

## 

### **6.2.3 Plasma Arc Welding**

Additional filler metal shall be used with the PAW process unless it can
be demonstrated by weld qualification that weld cracking and other
undesirable metallurgical conditions will not exist in the finished weld
made without filler metal (autogenous weld). This method of welding
shall be specified on an approved WPS.

## **6.3 PREHEATING**

Preheating shall not exceed 121°C (250°F) at any point on the assembly.
Actual welding shall begin immediately after preheating has reached the
temperature specified on the WPS or 121°C (250°F) maximum. Weld joints
involving alloys with magnesium levels \>3.0% (including filler alloys),
shall not be preheated above 65°C (150°F).

## **6.4 INTERPASS TEMPERATURE**

a.  In weld joints between different base metal types and thickness, the
    higher of the preheat requirements of the joint members shall apply.

b\. The temperature of the assembly shall not exceed 177 °C (350°F).
However, interpass temperatures may reach as high as 343°C (650°F) in
provided that the weldment is solution heat treated and aged (as
applicable to the alloy) using an appropriate post-weld heat treatment.

## **6.5 POST-WELD HEAT TREATMENT (PWHT)**

Postweld heat treatment, when required by the engineering drawing or
WPS, shall be performed after completion of all welding in accordance
with NASA/JSC PRC-2002, as applicable. Vibratory techniques are not
prohibited but shall not be used in place of thermal treatments. All
postweld inspections shall be applied immediately following all post
weld heat treatment activities.

**6.6 WELD REPAIRS AND WELDED REPAIRS TO BASE METAL**

All weld rework and welded repairs shall be documented on an appropriate
discrepancy report (DR) or weld repair record (WRR) form and shall be
performed using the WPS used for the original weld, a specific qualified
WPS for that repair, or as approved by the responsible M&P engineering
organization. Rework and repairs shall meet all of the requirements of
the original drawing and any additional requirements documented in the
WPS. Weld rework and repair does not include the correction of
dimensional or other deficiencies of the groove/bevel preparation of
weld joints by "buttering" or build up provided the area corrected by
welding is fully consumed in the final weld. Also, the following
requirements shall apply in the weld repair activity:

a.  [Defect Removal]{.underline}. Defect removal shall be by means of
    grinding, chipping, machining, thermal gouging or a combination of
    these methods. Thermal gouging and cutting shall require the
    excavated surface or cavity be finished to sound metal by a method
    determined suitable by the organization. The final repair cavity
    shall be of a configuration suitable for welding. The excavation
    shall be subjected to visual and/or other NDE examinations to ensure
    defect removal prior to welding. Weld repairs shall be adequately
    documented by the use of a weldment map or other record with
    sufficient detail to ensure identification of the weldment,
    identification of repair location(s), and type of defect.

b.  [Repair]{.underline}. No more than two weld attempts shall be made
    to successfully repair a rejected flaw. If a second attempt is
    unsuccessful, a discrepancy report requiring review and
    dispositioning by the responsible Material Review Board (MRB) shall
    be generated.

c.  [Straightening]{.underline}. Welds or adjacent base metal which have
    been deformed by the welding operation may be straightened. All
    straightening operations shall take place at temperatures not to
    exceed the determined critical temperature for that alloy.
    Straightening operations determined to be severe in nature shall be
    reviewed and approved by the responsible M&P engineering authority
    prior to the operations taking place. All straightening operations
    shall be performed prior to any final inspection.

d.  [Base Metal Repairs.]{.underline} Repairs to base metal anomalies
    shall be brought to the attention of the NASA/JSC M&P organization
    for consideration of cause, prior to repair activities.

# 

# **7.0 PROCESS VERIFICATION**

Process verification shall consist of nondestructive examination(s)
(NDE), as described in sections 7.1 to 7.3. In addition, the
manufacturer shall assure that the fabrication activities are carried
out in a manner that meets the requirements of this process
specification.

## 

## **7.1 INSPECTION**

Unless otherwise specified in design documentation, all inspections
(examinations) detailed herein are required to include all welds in a
structure.

1.  **[Class A Inspection]{.underline}**

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a)  Class A welds require visual (VT), surface, and subsurface NDE.
    Surface inspections shall be accomplished using the liquid penetrant
    (PT) inspection process. Surface inspections shall be accomplished
    using the PT, Type I, Level 3 or 4 process and shall be performed
    per AWS D1.2. Results of all surface inspections for Class A joints
    shall utilize the Class A acceptance criteria in Appendix A.
    Subsurface inspections shall be accomplished using the radiographic
    (RT) inspection process and shall be performed per AWS D1.2.

b)  In cases where the Class A inspection is designated for any weld
    having a configuration which renders adequate RT methods
    impractical, an alternate examination method shall be utilized as
    approved by the responsible NASA/JSC M&P engineering organization.

c)  When the PT method is selected and approved as a complete alternate
    to RT for multipass welds, inspections shall be performed on the
    root pass, each 1/4" thick layer of weld metal, and the final or
    cover pass.

d)  When the ultrasonic (UT) inspection method is selected as an
    alternate to RT, it shall be performed per AWS D1.2.

**7.1.2 [Class B Inspection]{.underline}**

Unless otherwise specified in design documentation, Class B welds
require VT and surface NDE only. Surface inspections shall be
accomplished using the PT, Type I, Level 3 or 4 process and shall be
performed per AWS D1.2. Results of all surface inspections for Class B
joints shall utilize the Class B acceptance criteria in Appendix A.

**7.1.3 [Class C Inspection]{.underline}**

Unless otherwise specified in design documentation, Class C welds
require VT only. Results of all VT inspections for Class C joints shall
utilize the Class C acceptance criteria in Appendix A.

### **7.1.4 Class D Inspection** 

Unless otherwise specified in design documentation, Class D welds
require only inspection to verify the type, nominal size, length,
location, and that the welds were left in a condition exhibiting good
workmanship practices. Good workmanship shall be defined as the presence
of uniform appearance and overall clean weld zones and the absence of
spatter, arc strikes, tool marks, and other obvious discontinuities that
would likely be questionable. Where a size is not specified, the nominal
weld size shall be per best shop practice and at the discretion of the
manufacturing organization with the intent to utilize single pass welds
wherever possible so as to avoid over-welding. A CWI is not required for
this inspection. This level of inspection may serve as a means of "in
process" or "self verification" where design and/or manufacturing
protocols permit.

## **7.2 VISUAL EXAMINATION REQUIREMENTS**

All visual inspections (VT) of all welds shall be performed by an
American Welding Society (AWS) Certified Welding Inspector (CWI). The
CWI certification must be current.

## **7.3 NON-DESTRUCTIVE EVALUATION (NDE)**

The NDE of welded joints shall be performed by personnel qualified in
accordance with the requirements of the applicable NDE process
specification. The NDE certification must be current. All nondestructive
inspections shall be performed in accordance with the appropriate
standards as referenced herein.

# 

# **8.0 PROCESS QUALIFICATION AND DOCUMENTATION REQUIREMENTS**

The WPS, PQR, and WPQ shall be prepared and retained as a permanent
record and made available upon request to the NASA/JSC M&P organization
for review**.** These procedures must contain, at a minimum, all of the
essential welding parameters (procedure qualification variables, etc.),
an identification of the welding equipment, and include any pertinent
tooling information. One copy of the WPS shall be maintained in the
vicinity of the welding station and shall be readily accessible by the
welders, inspectors, supervision, and engineering.

1.  **PROCEDURE QUALIFICATION VARIABLES**

Applicable to all processes, the process variables considered
"essential" and applicable to qualification of a welding
procees/procedure shall be all those as required by AWS B2.1 and to
include the following:

a.  A change from vertical downhill welding to vertical uphill or vice
    versa,

b.  A change from a stringer to a weave bead and vice versa,

c.  A change from multiple passes per side to a single pass per side,
    but not vice versa,

d.  As deemed necessary by the NASA/JSC M&P organization, an increase or
    decrease in in any one or more of the variables considered integral
    to the measured heat input (i.e., current, voltage, and travel
    speed) beyond that which was qualified. Where necessary, the
    procedure shall include weld tests that define the tolerance ranges
    of specifically identified parameters,

e.  For keyhole welding techniques, a change from keyhole to non-keyhole
    and vice versa.

    2.  **WELDING PROCEDURE SPECIFICATION**

A Welding Procedure Specification (WPS) is a qualified written working
procedure that must be developed before beginning production for each
unique weld type to be produced. Qualification support documentation in
the form of a Procedure Qualification Record (PQR) shall be maintained
on file to show proof of process/procedure capability using the WPS. The
WPS shall be traceable by means of serialized nomenclature and shall
show traceability to the applicable PQR(s). The WPS used for production
welding shall meet the requirements of AWS B2.1 and shall be certified
by the responsible M&P organization at the operating facility, prior to
use in production. If a qualified WPS does not exist prior to welding of
production parts, one shall be qualified according to AWS B2.1 "Standard
Test Weldments" at a minimum. "Prequalified" or "Standard Welding
Procedure Specifications" shall not be permitted for production use on
Class A or B welds made on flight hardware.

**8.3 PROCEDURE QUALIFICATION RECORD**

A Procedure Qualification Record (PQR) is documentation to support the
welding procedure specification to show proof of process/procedure
capability. A PQR shall be unique and traceable, by means of serialized
nomenclature. The PQR shall be process-specific and specific to a unique
weld type. Data required in the PQR shall include detailed descriptions
of the test coupon configurations and joint designs, all pertinent
material specifications, all pertinent essential process variables used,
all destructive and nondestructive test results from the qualification
sample set, and all required certifications from the approving
organization. The PQR shall be approved by the responsible M&P
organization at the operating facility.

## **8.4 WELDER PERFORMANCE QUALIFICATION**

A Welder Performance Qualification (WPQ) is documentation that shows
that a welder has been tested in accordance with PRC-0008 and shown
competent to produce a sound weld for a specific welding process/base
material/filler metal/position combination.

# 

# 

# **9.0 TRAINING AND CERTIFICATION OF PERSONNEL**

## **9.1 TRAINING**

At JSC, if welder training is considered necessary prior to
qualification/requalification of existing JSC welding personnel or for
the initial qualification of new hires, it shall be conducted in
accordance with TI-0000-04. For an outside JSC vendor, welder training
(when necessary) should consist of practice using the facility welding
equipment and a specific WPS to demonstrate proficiency, under the
supervision of a qualified/certified welder. Specific development of an
appropriate training program shall be the responsibility of the vendor.

## **9.2 WELDER QUALIFICATION**

Welding shall be performed by a welder qualified and certified in
accordance with NASA/JSC PRC-0008. Sufficiently detailed records shall
be maintained to demonstrate continuity of performance qualification on
a semi-annual (6 month) basis.

## **10.0 [DEVIATIONS AND WAIVERS]{.underline}**

Any deviations or waivers regarding the use of this process
specification shall be requested in writing. This request shall be
directed to the NASA/JSC M&P organization with the appropriate
justification and rationale. A written response will be provided upon
such a request.

**Appendix A**

**[WELD INSPECTION CRITERIA]{.underline}**

**[GENERAL]{.underline}** If any of the inspection conditions listed
herein conflict with the requirements of the engineering drawing, then
the more strict criteria shall govern. Pertinent to this Appendix, the
designation 'T' shall mean the nominal base metal thickness of the
thinnest component in the welded connection. Unless otherwise stated,
the criteria in this Appendix shall apply to all weld classes except
Class D. Acceptance criteria for Class D welds is detailed only in
Section 7.1 of this specification. Alternate and/or additional
acceptance criteria may be used for any weld class however, it shall be
specified in the design documentation.

**A1.0 [SIZE AND APPEARANCE]{.underline}**

**A1.1 GROOVE WELDS**

**[All Classes]{.underline} -** The minimum weld size shall be the size
(i.e., size = effective weld throat) specified on the drawing. If
profile requirements are not specified, the weld shall be convex. Where
a size is not specified, the penetration requirement shall be 100%.
Reinforcement requirements shall be as specified below.

**[Class A]{.underline} --** Groove welds shall be 100% penetration of
the joint section thickness.

**A1.2 FILLET WELDS**

**[All Classes]{.underline} -** The minimum weld size shall be the size
specified on the drawing (i.e., size = leg size). If profile
requirements are not specified, the weld may be slightly concave, flat,
or slightly convex. However, concave profiles shall have at least the
minimum throat for the size of weld specified. For intermittent welding,
the ends shall be be exempt from these profile requirements but shall be
outside the specified effective weld length. Where a size is not
specified, the weld size shall be a minimum of 75% of the thickness of
the thinner component. Reinforcement requirements shall be as specified
below.

**[Class A and B]{.underline} -** The weld size may fall below the size
specified by up to 1/16" or T/4, whichever is less, for 10% of the total
weld length ^(1)^.

**[Class C]{.underline} -** The weld size may fall below the size
specified by up to 1/16" or T/3, whichever is less, for 30% of the total
weld length ^(1)^.

(1) The weld length shall be the distance from end to end of the weld
    deposit or to a sharp change in direction of the weld where the
    angle of change in any direction is greater than 30 degrees at a
    radius of \<1/2".

**A2.0 [WELD REINFORCEMENT]{.underline}**

**A2.1 GROOVE AND FILLET WELDS**

**[All Classes]{.underline} -** Weld reinforcement (face and root) shall
not exceed that specified in Table A2.1a.

**TABLE A2.1a -- Weld Reinforcement Height Limits**

  ----------------------------------- -----------------------------------
  **Weld Width**                      **Reinforcement Height**

  **≤ ¼"**                            **1/16"**

  **¼" \< and ≤ ¾"**                  **1/8"**

  **¾"\< and ≤ 1-3/4"**               **3/16"**

  **\> 1-3/4"**                       **¼"**
  ----------------------------------- -----------------------------------

**A3.0 [MISALIGNMENT AND ANGULAR DISTORTION (Peaking)]{.underline}**

**[Class A]{.underline} -** Misalignment shall not exceed T/10 or 1/16",
whichever is less. Angular distortion (AD) shall not exceed 5 degrees.
If both misalignment and AD are present then the maximum allowable limit
of misalignment allowed shall be reduced accordingly by an amount equal
to the proportion that exists of the maximum allowable limit of AD, and
vice versa.

**[Class B and C]{.underline} -** Misalignment shall not exceed T/5 or
1/8", whichever is less. Combined misalignment and AD shall be subject
to the rules given above for Class A welds.

**A4.0 [SURFACE DISCOLORATION AND OXIDATION]{.underline}**

Weld zones shall not exhibit a burned appearance or contain loose
oxidation or scale attributable to atmospheric contamination.

**A5.0 [SURFACE ROUGHNESS]{.underline}**

**[All Classes]{.underline} --** On mechanically dressed (e.g., ground,
sanded, etc.) weld and adjacent surfaces within ½" of the weld toe,
surface roughness shall not exceed 63 μin.

**A6.0 [DISCONTINUITIES]{.underline}**

**[All Classes]{.underline} -** Weld discontinuities exceeding the
maximum allowable sizes for the applicable Class in Table A6.0 shall not
be allowed. Elongated discontinuities shall be defined as having a
length to width ratio of ≥ 3:1. Rounded discontinuities shall be defined
as having a length to width ratio \< 3:1.

For base metal thicknesses (T) ≥ 1/8", the following shall apply to
Table A6.0a:

> **[Class A]{.underline} -** Any discontinuity, except cracks and
> undercut, \<0.01" at its greatest dimension, shall not be considered.
>
> **[Class B]{.underline} -** Any discontinuity, except cracks and
> undercut, \<1/32" at its greatest dimension, shall not be considered.
>
> **[Class C]{.underline} -** Any discontinuity, except cracks and
> undercut, \<1/16" at its greatest dimension, shall not be considered.

**TABLE A6.0 - Maximum Allowable Discontinuity Sizes**

  -------------- ----------------- ---------------- ---------------- ----------------
  **LINEITEM**   **DISCONTINUITY   **Class A**      **Class B**      **Class C**
                 TYPE**                                              

  **1**          **Cracks in the   None allowed     None allowed     None allowed
                 weld or base                                        
                 metal (e.g.,                                        
                 longitudinal,                                       
                 transverse,                                         
                 crater, toe,                                        
                 etc.) ^(1)^**                                       

  **2**          **Undercut Depth  0.01" or 0.1T,   1/32" or 0.33T,  1/16" or 0.33T,
                 ^(1)^**           whichever is     whichever is     whichever is
                                   less             less ^(3)^       less ^(3)^

  **3**          **Arc Strike**    None allowed     None allowed     None allowed

  **4**          **Spatter**       None allowed     None allowed     None allowed

  **5**          **Elongated       None allowed     3/32" or 0.4T in 1/8" or 0.6T in
                 ^(1)^**                            length,          length,
                                                    whichever is     whichever is
                                                    less ^(4)^ Sum   less ^(4)^ Sum
                                                    of all visible   of all visible
                                                    indications      indications
                                                    shall be ≤3/8"   shall be ≤1/2"
                                                    or T in length,  in length, in
                                                    whichever is     any 1" of weld
                                                    less, in any 1"  length and
                                                    of weld length   ≤1.75" in any
                                                    and ≤3/4" in any 12" of weld
                                                    12" of weld      length ^(5)^
                                                    length ^(5)^     

  **6**          **Rounded ^(1)^** Surface: 1/16"   3/32" or 0.4T    1/8" or 0.6T
                                   or 0.3T          diameter         diameter,
                                   diameter,        whichever is     whichever is
                                   whichever is     less ^(2)^ Sum   less ^(2)^ Sum
                                   less ^(2)^       of all visible   of all visible
                                                    indications      indications
                                                    shall be ≤3/8"   shall be ≤1/2"
                                                    or 1.5T in       in any 1" of
                                                    length,          weld length and
                                                    whichever is     ≤1.75" in any
                                                    less, in any 1"  12" of weld
                                                    of weld length   length ^(5)^
                                                    and ≤3/4" in any 
                                                    12" of weld      
                                                    length ^(5)^     
  -------------- ----------------- ---------------- ---------------- ----------------

(1) For all discontinuities approaching a free edge (See Figure A6.0
    below) that are being considered, the closest edge of the
    discontinuity shall have clearance from the free edge ≥ 3X the
    largest of its dimensions or, ≥ 2X the nominal weld throat,
    whichever is greater.

(2) *Adjacent rounded discontinuities separated by ≤ 1X the length of
    the longer discontinuity shall be considered a single
    discontinuity.*

(3) *Undercut may be 2X the value permitted, but never to exceed 1/16",
    for a continuous or accumulated length of 2" in any 12" weld length
    or 15% of the total weld length where the weld length is less than
    12".*

(4) Adjacent elongated discontinuities separated by ≤ 3X the diameter of
    the larger discontinuity, shall be considered a single
    discontinuity.

(5) For weld lengths less than 12", the total sum of indications shall
    be an equivalent proportion of the weld length, to that given.

![](media/image2.png){width="2.4590277777777776in"
height="1.9916666666666667in"}

C = Clearance spacing between closest edge of discontinuity and free
edge

**FIGURE A6.0 -- [DISCONTINUITY APPROACHING FREE EDGE]{.underline}**