+--------------+----------------------------------+-------------------+
| ![](media/i  | Pressure Vessel Engineering Note | **Doc. No.**      |
| mage1.png){w | (short)                          |                   |
| idth="0.5in" |                                  | **Rev. No. 0**    |
| height       | For the                          |                   |
| ="0.53819444 |                                  | **Date: 27        |
| 44444444in"} | 3.9-GHz Helium Vessel, Cavity #4 | January 2009**    |
|              |                                  |                   |
|              |                                  | **Page** **1 of   |
|              |                                  | 26**              |
+--------------+----------------------------------+-------------------+

![](media/image1.png){width="1.2979166666666666in"
height="1.3965277777777778in"}

**FERMILAB**

Technical Division

Pressure Vessel Engineering Note

For the

3.9-GHz Helium Vessel, Cavity #4

(short version referencing cavity #5)

  ------------------------------------------------ ----------------------
  Authors: M. Wong, G. Galasso, Harry Carter, Tom  Date: 27 January 2009
  Peterson, Phil Pfund, Dan Olis, Tug Arkan        

  ------------------------------------------------ ----------------------

**[Table of Contents]{.underline}**

[Section]{.underline} [Page Number]{.underline}

**[General introduction -- exceptional vessel Pg 3]{.underline}**

**[Pressure vessel engineering note form (FESHM 5031) Pg
4]{.underline}**

**[Appendix A -- Extended Engineering Note]{.underline}**

**Introduction Pg 8**

**Exceptional vessel discussion and note summary Pg 9**

**Vessel description Pg 10**

**Analysis Pg 14**

**Welding information Pg 16**

**[Appendix B -- 2.3 bar Pressure Test Results Pg 21]{.underline}**

**[Appendix C -- Cavity Processing Information Pg 24]{.underline}**

**[[General introduction -- exceptional vessel]{.underline}]{.mark}**

[This engineering note for dressed cavity #4 references the note for
cavity #5 where the information is almost identical. For the same
reasons as Cavity #5, Cavity #4 is an exceptional vessel. Starting with
the Extended Engineering Note on page 8, only the differences from
cavity #5 are detailed here. Specifically, the highlighted text details
the differences. The non-highlighted text is identical to its
counterpart in the Cavity #5 note.]{.mark}

**PRESSURE VESSEL ENGINEERING NOTE**

**PER FESHM CHAPTER 5031**

Prepared by: [Mayling Wong, Germano Galasso, Tom Peterson, Phil Pfund,
Harry Carter, Dan Olis, Tug Arkan]{.underline}

Preparation date: [27 January 2009]{.underline}

1\. [Description and Identification]{.underline}

Fill in the label information below:

This vessel conforms to Fermilab ES&H Manual

Chapter 5031

Vessel Title [3.9-GHz Helium Vessel, Cavity #4]{.underline}

Vessel Number [IND-127]{.underline}

Vessel Drawing Number [5525.000-ME-440598 (Rev. C)]{.underline}

Maximum Allowable Working Pressures (MAWP):

Internal pressure Warm [2.0-bar (29.0 psia)]{.underline}

Internal Pressure Cold [2.0 bar (29.0 psia)]{.underline}

External Pressure [1.0-bar (14.5-psia)]{.underline}

Working Temperature Range [-457]{.underline} oF - [100]{.underline} oF

Contents [Superfluid helium]{.underline}

Designer/Manufacturer [FNAL]{.underline}

Test Pressure (if tested at Fermi) Acceptance **Document per Chapter
5034**

Date: **of the Fermilab ES&H Manual**

[2.3 bar]{.underline}

\_\_[33.5\_\_]{.underline}PSI**D**, Hydraulic Pneumatic [X]{.underline}

Accepted as conforming to standard by

of Division/Section\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Date:\_\_\_\_\_\_\_\_
**Actual signature required**

NOTE: Any subsequent changes in contents,

pressures, temperatures, valving, etc., which

affect the safety of this vessel shall require

another review.

Reviewed by: Date:

Director\'s signature (or designee) if the vessel is for manned areas
but doesn\'t conform to the requirements of the chapter.

Date:

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_Date:
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

ES&H Director Concurrence

Amendment No.: Reviewed by: Date:

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_\_\_\_
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_\_\_\_\_
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Lab Property Number(s):

Lab Location Code: [Meson Detector Building]{.underline} (obtain from
safety officer)

Purpose of Vessel(s): [LHe containment for nine-cell 3.9-GHz
superconducting]{.underline}

[Radio frequency cavity]{.underline}

Vessel Capacity/Size: [3.4-L]{.underline} Diameter:
[5.5"(140mm)]{.underline} Length: [19.9"(505.92mm)]{.underline}

Normal Operating Pressure (OP) [0.02-bar (0.25-psia)]{.underline}

MAWP-OP = [28.75]{.underline} PSID

List the numbers of all pertinent drawings and the location of the
originals.

[Drawing \#]{.underline} [Location of Original]{.underline}

[5525-ME-440598 Rev B]{.underline} [IDEAS FERMI TDM]{.underline}

[5520-ME-426450 Rev F]{.underline} [IDEAS FERMI TDM]{.underline}

[5520-ME-426321 Rev B]{.underline} [IDEAS FERMI TDM]{.underline}

[5520-MB-426252 Rev C]{.underline} [IDEAS FERMI TDM]{.underline}

(Above are the top-level drawings, see Appendix B, "drawing tree", in
the design note)

2\. [Design Verification]{.underline}

Is this vessel designed and built to meet the Code or "In-House Built"
requirements?

Yes No [X]{.underline}

# If "No" state the standard that was used [ASME Code, Section VIII, Div 1 and Div 2 with finite element analysis and reference to published mechanical data for niobium and NbTi (where code data were not available)]{.underline} 

> Demonstrate that design calculations of that standard have been made
> and that other requirements of that standard have been satisfied.
>
> Skip to part 3 "system venting verification."
>
> Does the vessel(s) have a U stamp? Yes\_\_\_\_\_ No [X]{.underline} .
> If \"Yes\", complete section 2A; if \"No\", complete section 2B.

A**.** Staple photo of U stamp plate below.

Copy \"U\" label details to the side

Copy data here:

![](media/image2.wmf){width="7.611111111111111in"
height="5.222222222222222in"}

Figure 1. ASME Code: Applicable Sections

**2B.**

[Summary of ASME Code]{.underline}

[CALCULATION RESULT]{.underline}

(Required thickness or stress

Reference ASME level vs. actual thickness

[Item]{.underline} [Code Section]{.underline} [calculated stress
level)]{.underline}

(see Design Note)

vs

vs

vs

vs

3\. [System Venting Verification]{.underline} (See Figure A4 for vent
system schematic

\- drawing 4906.320-ME-440302)

Does the venting system follow the Code UG-125 through UG-137?

> Yes [X]{.underline} No\_\_\_

Does the venting system also follow the Compressed Gas Association
Standards S-1.1 and S-1.3?

Yes [X]{.underline} No\_\_\_\_\_

A "no" response to both of the two proceeding questions requires a
justification and statement regarding what standards were applied to
verify system venting is adequate.

[List of reliefs and settings]{.underline}:

[Manufacturer]{.underline} [Model \#]{.underline} [Set
Pressure]{.underline} [Flow Rate]{.underline} [Size]{.underline}

[BS&B]{.underline} [LPS]{.underline} [12-psig]{.underline} [2188-SCFM
air]{.underline} [3-inch]{.underline}

[Hylok 700]{.underline} [CV5-F12N-25]{.underline} [5-psig
\*]{.underline} [Cv=5.2]{.underline} [3/4\"]{.underline}

\*The valve was reset to 5-psig from 25-psig. The model number reflects
the

original set pressure of 25-psig.

4\. [Operating Procedure]{.underline}

Is an operating procedure necessary for the safe operation of this
vessel?

Yes\_\_\_\_\_ No [X]{.underline} (If \"Yes\", it must be appended)

5\. [Welding Information]{.underline}

Has the vessel been fabricated in a non-code shop? Yes [X]{.underline}
No

> If \"Yes\", append a copy of the welding shop statement of welder
> qualification (Procedure Qualification Record, PQR) which references
> the Welding Procedure Specification (WPS) used to weld this vessel.
>
> See "Welding Information" Section in Appendix A

6\. [Existing, Used and Unmanned Area Vessels]{.underline}

Is this vessel or any part thereof in the above categories?

Yes\_\_\_\_\_ No [X]{.underline}

> If \"Yes\", follow the requirements for an Extended Engineering Note
> for Existing, Used and Unmanned Area Vessels.

7\. [Exceptional Vessels]{.underline}

Is this vessel or any part thereof in the above category?

Yes [X]{.underline} No

> If \"Yes\", follow the requirements for an Extended Engineering Note
> for Exceptional Vessels.

**[Appendix A -- Extended Engineering Note]{.underline}**

**Introduction**

The 3.9 GHz "dressed cavity", cavity #4, is a niobium superconducting
radio frequency (RF) cavity surrounded by a helium vessel which will be
filled with liquid helium (so liquid helium surrounds the niobium RF
cavity) at temperatures as low as 1.8 K. The cavity will be performance
tested in the Horizontal Test Stand (HTS) at the Meson Detector Building
at Fermi National Accelerator Laboratory (Fermilab) before being
installed in a cryostat with three other 3.9 GHz dressed cavities. The
cryostat with four dressed cavities will be shipped to DESY, in Hamburg,
Germany, to be installed in the FLASH-linac (former TTF2-linac). This
document summarizes how the helium vessel for cavity #4 follows the
requirements of the FESHM 5031 \[ref 1\]. This document and supporting
documents for the 3.9 GHz helium vessel engineering note and also for
the 3.9 GHz cryomodule may be found at:

<http://ilc-dms.fnal.gov/Workgroups/CryomoduleDocumentation/3rd-Harmonic-Cryomodule-for-DESY/>

[Cavity #4 is the sixth dressed cavity that will be tested in HTS. The
designs of the dressed cavity are almost identical to Cavity #5. The
only difference is in one part of the helium vessel design. The
difference is detailed in the "Vessel Description" of Appendix A of this
engineering note. The fabrication of Cavity #4 follows almost the exact
the same procedure as the fabrication for Cavity #5. Several steps in
the welding procedure differ in an effort to optimize the fabrication
process. How the fabrication for Cavity #4 differs from Cavity #5 is
detailed in the section titled "Welding Information" of Appendix A of
this engineering note.]{.mark}

...

**Exceptional Vessel Discussion and Extended Engineering Note Summary**

*Reason for Exception*

The 3.9-GHz dressed cavity as a helium vessel has materials and complex
geometry that are not conducive to complete design and fabrication
following the ASME Code \[ref 2\]. Parts of the vessel are made of
niobium and an alloy that is 45% niobium/55% titanium. Neither of these
materials is approved in the Code.

However, we show that the vessel is safe at a level that is consistent
with the Code in accordance with FESHM 5031. Since the vessel design and
fabrication did not exactly follow the guidelines given by the Code, the
vessel requires a Director's Exception. [(The page numbers in Table A1
refer to the pages in the Cavity #5 engineering note.)]{.mark}

[Table A1 -- Specific areas of exception to the ASME code]{.underline}

  ------------------------------- --------------- ------------------------------
  **Location or procedure**       **Reference**   **Explanation for exception**

  Niobium material                pg 17           Used for its superconducting
                                                  properties, not explicitly
                                                  allowed by the code

  Calculated stress in Nb cavity  pg 41           Worst case tuning extension
  at the iris.                                    (0.5 mm) with internal
                                                  pressure at room temperature
                                                  (82.4 MPa vs 60 MPa
                                                  allowable). This stress is
                                                  self-limited by the tuner and
                                                  results at worst in an offset
                                                  of the neutral tuning
                                                  position.

  Niobium-Titanium material       pg 19           Used for compatibility in
                                                  welding with niobium and
                                                  titanium, a transition between
                                                  the two metals

  Partial penetration welds in Ti pp 79 - 85      Care not to burn through the
  and between NbTi and Ti                         material

  Weld procedure specification    pp 74           The 0.8 factor taken on
  (WPS), procedure qualification                  allowable material stress per
  record (PQR), and welder                        FESHM 5031 is intended exactly
  performance qualification (WPQ)                 for this issue, to mitigate
  were either not performed, or                   incomplete code-specified
  initiated after completion of                   information.
  the work                                        

  Incomplete testing of bulk and  pp 74           See note above regarding 0.8
  weld affected zone material                     factor.

  No X-ray or ultrasonic          pg 74           Access difficulty. Samples
  inspections of welds (Div 2                     were welded, cut, polished,
  requires 100% radiography, plus                 and photographed instead in
  10% ultrasonic testing on                       order to establish degree of
  welds.)                                         weld penetration.
  ------------------------------- --------------- ------------------------------

...

*Fabrication*

Detailed welding information is included in this engineering note. A
fabrication procedure, associated material specifications, and welders'
certifications are compiled in a second document with the file name
"[Cavity-4-Matl_Weld_Certs.doc]{.mark}".

\...

*Pressure Test*

The dressed cavity was pressure tested to 2.3 bar, 1.15 times the MAWP
of 2.0 bar.

\...

**Vessel Description**

...

A complete drawing tree is shown in Figure A1. The top level and second
level assembly drawings are copied in the following figures for
reference here. A complete set of drawings is at:

<http://ilc-dms.fnal.gov/Workgroups/CryomoduleDocumentation/3rd-Harmonic-Cryomodule-for-DESY/DressedCavityDrawings/>
and is also archived at:

<http://tdserver1/project/TDarchivedDrawings/drawings/>

[The design of Cavity #4 is almost the same as for Cavity #5. The
drawings shown in Figure A1 have been updated to reflect the changes.
The only design change for Cavity #4 is the thickness of the bellows
cuff design (drawing MB-457115) at the bellows-to-shell joint in the
helium vessel. The thickness of the cuff is 2-mm. The cuff design allows
for a full penetration TIG weld of the bellows assembly to the helium
vessel shell. The joint detail is shown in Figure A29 (weld #7,
#8).]{.mark}

...

![](media/image3.wmf)

[[Figure A1. Dressed cavity #4 drawing tree]{.underline}]{.mark}

![](media/image4.png){width="7.577083333333333in"
height="5.834027777777778in"}

[[Figure A2 -- Helium Vessel for the 3.9-GHz Cavity, assembled in the
welding fixture (Drawing 5520.000-ME-440598)]{.underline}]{.mark}

...

![](media/image5.png){width="7.826388888888889in"
height="6.020138888888889in"}

[[Figure A4 -- Helium Vessel Weldment for 3.9-GHz Dressed Cavity
(Drawing 5520.000-ME-426450)]{.underline}]{.mark}

...

**Welds Simulation**

[This section is identical to that for cavity #5 but is included here
since the welds \# 7 and 8 are different for cavity #4. (See "Welding
Information" starting on pg. 16 in this engineering note.) The
simulation is identical since minimal weld penetration and a
conservatively small joint area are assumed. For cavity #4, the actual
fused areas for these welds increased, so the analysis is just more
conservative and was not modified.]{.mark}

...

**Analysis**

...

**2^nd^ Load Case**

[Primary + Secondary stress evaluation at room temperature (worst
case)]{.underline}

[All identical to cavity #5 engineering note, pp. 38 -- 49. Table A12,
which shows the cavity iris calculated stress, is copied here since this
includes the one exceptional stress.]{.mark}

...

[Table A12 -2^nd^ Load Case: Niobium Cavity. Linearized Stress Intensity
summary]{.underline}

+-----+-----------------+-------+-----------+----------+------------+
| SCL | Component and   | Mat   | Stress    |          | Acceptance |
|     |                 | erial | Category  |          | Criteria   |
|     | Evaluation      |       | and Value |          |            |
|     | Region          |       |           |          | \[MPa\]    |
|     |                 |       | L         |          |            |
|     |                 |       | inearized |          |            |
|     |                 |       | Stress    |          |            |
|     |                 |       | Intensity |          |            |
|     |                 |       |           |          |            |
|     |                 |       | \[MPa\]   |          |            |
+-----+-----------------+-------+-----------+----------+------------+
| **  | Cavity:         | Nb    | P~M~+Pb+Q | 11.22    | ≤ 3∙S=60   |
| J** |                 | RRR   |           |          |            |
|     | Cavity/Nb-Ti    |       |           |          |            |
|     | Joint           |       |           |          |            |
|     |                 |       |           |          |            |
|     | Weld Region     |       |           |          |            |
+-----+-----------------+-------+-----------+----------+------------+
| **  | Cavity:         | Nb    | P~M~+Pb+Q | 11.31    | ≤ 3∙S=60   |
| Y** |                 | RRR   |           |          |            |
|     | Cavity/Nb-Ti    |       |           |          |            |
|     | Joint           |       |           |          |            |
|     |                 |       |           |          |            |
|     | Weld Region     |       |           |          |            |
+-----+-----------------+-------+-----------+----------+------------+
| **  | Cavity:         | Nb    | P~M~+Pb+Q | 20.81    | ≤ 3∙S=60   |
| Z** |                 | RRR   |           |          |            |
|     | End Cells       |       |           |          |            |
|     | Region          |       |           |          |            |
+-----+-----------------+-------+-----------+----------+------------+
| **  | Cavity:         | Nb    | P~M~+Pb+Q | 82.43    | ≤ 3∙S=60   |
| D** |                 | RRR   |           |          |            |
|     | Mid Region-     |       |           |          |            |
|     | Iris            |       |           |          |            |
+-----+-----------------+-------+-----------+----------+------------+
| **  | Cavity:         | Nb    | P~M~+Pb+Q | 25.59    | ≤ 3∙S=60   |
| F** |                 | RRR   |           |          |            |
|     | Mid Region-     |       |           |          |            |
|     | Equator         |       |           |          |            |
+-----+-----------------+-------+-----------+----------+------------+

\...

**Welding Information**

[All welds were designed, welded, and qualified as per Cavity #5 except
those highlighted in Tables A24-1 and A24-2.]{.mark} ...

[Table A24-1 - 3^rd^ harmonic dressed cavity #4 weld
summary]{.underline}

+----+----------------+----------+-----+-----------------------------+
| We | Weld           | Drawing  | T   | How qualified and other     |
| ld | description    | or       | ype | notes                       |
|    |                | r        | of  |                             |
| N  |                | eference | w   |                             |
| o. |                |          | eld |                             |
+----+----------------+----------+-----+-----------------------------+
| 1  | Nb cavity end  | M        | e-b | Parameters developed based  |
|    | cell to Nb     | D-442202 | eam | on microscopic or           |
|    | tube end       |          |     | metallographic analysis of  |
|    | flange, input  |          |     | cut, etched and polished    |
|    | coupler end    |          |     | weld samples. Welded at     |
|    |                |          |     | Sciaky.                     |
+----+----------------+----------+-----+-----------------------------+
| 2  | Nb cavity end  | M        | e-b | Same as above. Welded at    |
|    | cell to Nb     | D-442201 | eam | Sciaky.                     |
|    | tube end       |          |     |                             |
|    | flange,        |          |     |                             |
|    | non-input      |          |     |                             |
|    | coupler end    |          |     |                             |
+----+----------------+----------+-----+-----------------------------+
| 3  | NbTi large     | M        | e-b | Same as above. Welded at    |
|    | conical end    | D-442202 | eam | Sciaky.                     |
|    | cap A to Nb    |          |     |                             |
|    | tube end       |          |     |                             |
|    | flange, input  |          |     |                             |
|    | coupler end    |          |     |                             |
+----+----------------+----------+-----+-----------------------------+
| 4  | NbTi small     | M        | e-b | Same as above. Welded at    |
|    | conical end    | D-442201 | eam | Sciaky.                     |
|    | cap B to Nb    |          |     |                             |
|    | tube end       |          |     |                             |
|    | flange,        |          |     |                             |
|    | non-input      |          |     |                             |
|    | coupler end    |          |     |                             |
+----+----------------+----------+-----+-----------------------------+
| 5  | Nb end tube to | M        | e-b | Same as above. Welded at    |
|    | Nb conical     | D-442202 | eam | Sciaky.                     |
|    | flange A,      |          |     |                             |
|    | coupler end    |          |     |                             |
+----+----------------+----------+-----+-----------------------------+
| 6  | Nb end tube to | M        | e-b | Same as above. Welded at    |
|    | Nb conical     | D-442201 | eam | Sciaky.                     |
|    | flange B,      |          |     |                             |
|    | non-coupler    |          |     |                             |
|    | end            |          |     |                             |
+----+----------------+----------+-----+-----------------------------+
| 7  | Ti bellows to  | M        | [TI | [Same as above. Welded at   |
|    | Ti tube        | C-457114 | G]{ | Hi-Tech.]{.mark}            |
|    |                |          | .ma |                             |
|    |                |          | rk} |                             |
+----+----------------+----------+-----+-----------------------------+
| 8  | Ti bellows to  | M        | [TI | [Same as above. Welded at   |
|    | Ti tube        | C-457114 | G]{ | Hi-Tech.]{.mark}            |
|    |                |          | .ma |                             |
|    |                |          | rk} |                             |
+----+----------------+----------+-----+-----------------------------+
| 9  | NbTi conical   | M        | e-b | [Same as weld numbers 1 - 6 |
|    | end piece to   | E-440598 | eam | above. Welded at            |
|    | Ti cylinder,   | detail C |     | Sciaky.]{.mark}             |
|    | coupler end    | and      |     |                             |
|    |                | "H       |     |                             |
|    |                | e_vessel |     |                             |
|    |                | to       |     |                             |
|    |                | cavity   |     |                             |
|    |                | w        |     |                             |
|    |                | eld.ppt" |     |                             |
+----+----------------+----------+-----+-----------------------------+
| 10 | NbTi conical   | M        | e-b | [Same as weld numbers 1 --  |
|    | end piece to   | E-440598 | eam | 6 above. Welded at          |
|    | Ti spacer      | detail D |     | Sciaky.]{.mark}             |
|    | ring,          | and      |     |                             |
|    | non-coupler    | "H       |     |                             |
|    | end            | e_vessel |     |                             |
|    |                | to       |     |                             |
|    |                | cavity   |     |                             |
|    |                | w        |     |                             |
|    |                | eld.ppt" |     |                             |
+----+----------------+----------+-----+-----------------------------+
| 11 | Ti spacer ring | M        | TIG | Welded by Dan Watkins,      |
|    | to Ti          | E-440598 |     | Fermilab, in the A0 glove   |
|    | cylinder,      | detail D |     | box. WPQ and PQR from Alloy |
|    | non-coupler    | and      |     | Weld Inspection Company.    |
|    | end            | "H       |     |                             |
|    |                | e_vessel |     |                             |
|    |                | to       |     |                             |
|    |                | cavity   |     |                             |
|    |                | w        |     |                             |
|    |                | eld.ppt" |     |                             |
+----+----------------+----------+-----+-----------------------------+

[The following information explains the welding procedure of the helium
vessel for cavity #4 for weld numbers 7 -- 11 (in Table A24-1):]{.mark}

[All the parts for this specific helium vessel were machined and TIG
welded at Hi-Tech.  ]{.mark}

[There are three welds connecting the helium vessel to the cavity:  an
EB weld joining the bottom of the vessel to the large conical end cap
(weld #9), an EB weld joining the titanium slip ring to the small
conical end cap (weld #10), and a TIG fillet weld joining the vessel to
the slip ring (weld #11).]{.mark}  We are not allowed to do full
penetration EB welds because the RF people want to avoid any NbTi or Ti
vapor deposition on the half-cells.  They believe it will negatively
affect heat transfer to the liquid helium in the vessel.

[The two EB welds were done at Sciaky.  In the Power Point presentation
you will see pictures of the cut, etched and polished weld samples
performed using the same weld parameters.  The TIG weld was done at
Fermilab by Dan Watkins.  You will also see pictures of the preliminary
weld samples Dan produced in the Power Point presentation. His WPQ is
provided.]{.mark}

[Weld #11, where there is a final fillet weld joining the titanium
spacer ring to the titanium cylinder, is a complete circumferential
weld. The procedure for Cavity #4 to arrive at the weld is slightly
different than for the same weld in Cavity #5. The weld was built up in
increments, then allowed to cool so that the frequency spectrum can be
monitored. The additional steps of cooling the weld and monitoring the
frequency spectrum were taken for Cavity #4 and were not done for Cavity
No. 5. The final resulting weld is the same for both cavities.]{.mark}

[Table A24-2 below lists the welds that are different between Cavities 4
and 5.]{.mark}

[[Table A24-2 -- Summary of Differences in the Welds of Cavities #5 and
#4]{.underline}]{.mark}

  -------- ----------------- --------------------- ----------------------
  **Weld   **Description**   **Cavity No. 5**      **Cavity No. 4**
  No.**                                            

  7        Ti bellows to Ti  E-beam weld at Sciaky TIG weld at Hi-Tech --
           tube              -- 75% penetration    full penetration

  8        Ti bellows to Ti  E-beam weld at Sciaky TIG weld at Hi-Tech --
           tube              -- 75% penetration    full penetration

  9        NbTi conical end  Welds later certified No radiographic
           piece to Ti       by radiographic       analysis. Weld
           cylinder, coupler analysis, tensile and procedure is the same
           end               bend tests performed  as for Cavity #5.
                             on weld samples via   
                             Packer Engineering    
                             (pending).            

  11       Ti spacer ring to For final fillet      For final fillet weld,
           Ti cylinder,      weld, weld in         weld in increments
           non-coupler end   increments around     around circumference,
                             circumference,        allow part to cool,
                             working towards a     monitor frequency
                             complete weld         spectrum, repeat to
                                                   work towards a
                                                   complete weld
  -------- ----------------- --------------------- ----------------------

Weld documents are available at:

<http://ilc-dms.fnal.gov/Workgroups/CryomoduleDocumentation/3rd-Harmonic-Cryomodule-for-DESY/helium-vessel-engineering-note/>

[These include:]{.mark}

[]{.mark}

["Helium Vessel to Cavity." This PowerPoint file by Mike Foley describes
the helium vessel weld setup and process. Weld samples are also
shown.]{.mark}

[]{.mark}

["Fermilab Welder Performance Qualification (WPQ)." The final closure
titanium TIG weld was performed by Dan Watkins.]{.mark}

[]{.mark}

["Procedure Qualification Record (PQR) for GTAW / Manual Process for
Fermilab". The final closure titanium TIG weld was created at
Fermilab.]{.mark}

[]{.mark}

["Procedure Qualification Record (PQR) for Electron Beam Welding process
at Sciaky." The niobium cavity was welded at Sciaky. Also, the NbTi / Ti
welds were created at Sciaky.]{.mark}

[]{.mark}

["Procedure for TIG Welding Helium Vessels to 3.9 GHz 3^rd^ Harmonic
Cavities." The procedure details the steps in making the final three
welds to attach the cavity to the titanium shell.]{.mark}

![](media/image6.jpeg){width="0.9166666666666666in"
height="0.9166666666666666in"}

[Figure A29 - Welds forming the Cavity #4 Helium Vessel Pressure
Boundary]{.underline}

...

**Weld Details: Weld numbers 7, 8 from Figure A29**

![](media/image7.jpeg){width="3.333464566929134in"
height="3.333464566929134in"}

+-------------+-------------+-------------+-------------+-------------+
| Weld Number | Weld        | Type of     | Full        | Location of |
|             | Description | weld        | Penetration | Weld Stress |
|             |             |             | or Partial  | Calculation |
|             |             |             | Penetration | in this     |
|             |             |             |             | Eng. Note   |
+-------------+-------------+-------------+-------------+-------------+
| 7           | Titanium    | []{.mark}   | []{.mark}   | []{.mark}   |
|             | bellows to  |             |             |             |
|             | titanium    | [           | [F          | \-          |
|             | tube        | TIG]{.mark} | ull]{.mark} |             |
+-------------+-------------+-------------+-------------+-------------+
| 8           | Titanium    | []{.mark}   | []{.mark}   | []{.mark}   |
|             | bellows to  |             |             |             |
|             | titanium    | [           | [F          | \-          |
|             | tube        | TIG]{.mark} | ull]{.mark} |             |
+-------------+-------------+-------------+-------------+-------------+

...

**[Appendix B -- 2.3 bar Pressure Test]{.underline}**

[Pressure test results for Cavity]{.mark} 4.

Test Procedure

+-----------------------------------------------------------------------+
| See attached sketch for test flow schematic.                          |
|                                                                       |
| Following paragraph 8.3 of Section VIII, Div 2 of the ASME pressure   |
| vessel code:                                                          |
|                                                                       |
| The pressure in the vessel shall be gradually increased to not more   |
| than half the test pressure (which means not more than 17 psig). Then |
| increase pressure in steps of 2 to 3 psi until the final test         |
| pressure of 33.5 psig is reached. Then back the pressure off to the   |
| MAWP of 29 psig and stop. Verify that no leaks occur by watching the  |
| system pressure for 3 minutes. Reduce pressure to half of the test    |
| pressure (to 17 psig), then enter the cave for a visual inspection of |
| the vessel.                                                           |
|                                                                       |
| Note 1: since this vessel and test are a joint TD and AD effort,      |
| safety officers from both TD and AD will witness the test.            |
|                                                                       |
| Note 2: the pressure test will also include an RF frequency           |
| measurement before, during, and after pressurization to check for any |
| permanent deformation of the cavity.                                  |
|                                                                       |
| Note 3: The cavity will arrive at the test site backfilled with clean |
| gas at 0-psig and will remain unchanged during the test.              |
+-----------------------------------------------------------------------+

![](media/image8.jpeg){width="4.563888888888889in"
height="6.3590277777777775in"}

**Report on the pressure test results.**

People present were: Elvin Harmes, Andy Hocker, Timergali Khabiboulline
(RF test), Raymond Lewis, Tom Peterson, Allan Rowe, Rich Ruthe, Bill
Soyars. Roger Milholland and Steve Cozzens were the AD cryo technicians
who performed the test.

Pressure tests and pressure hold at the MAWP follow the general
guidelines presented in ASME pressure vessel code, Section VIII, Div 2,
Part 8-3. The table below shows the actual pressure levels for each
pause and what was done at that pressure. This table or something
similar may be incorporated into procedures for future dressed cavity
pressure tests. Total time for the test, not including setup and
tear-down time, was about 20 minutes.

  ----------------------- ----------------------- -----------------------
  Pressure (psig) (psig   Dwell time (minutes)    Activity at pressure
  was differential                                
  pressure for this test)                         

                                                  

                                                  

                                                  

                                                  

                                                  

                                                  

                                                  

                                                  

                                                  

                                                  

                                                  

                                                  
  ----------------------- ----------------------- -----------------------

**[[Appendix C -- Cavity processing information]{.mark}]{.underline}**

The bare niobium cavity #4 was processed and baked as described in the
tables below, excerpted from Allan Rowe's spreadsheet, "SCRF 3rd Harm
Cavity Processing Chart.xls".

![](media/image9.wmf)

![](media/image10.wmf)

![](media/image11.wmf)