ICS 77.140.75 
H 48 
                                                         GB 
National Standard of the People’s Republic of China  
    GB 3087 –– ×××× 
Replaces GB 3087-1999  
________________ __________________ _______________ ______________ 
 
  
Seamless steel tubes for low and medium pressure boiler 
(ISO 9329-1: 1989, NEQ) 
 
(Draft submitted for Approval) 
 
     
Issue Date: ×××× -××-××                   Implementation Date: ×××× -××-×× 
____________________________________________________________________ 
Issued by the  General Administration of Quality Supervision,  Inspection 
and Quarantine, The People’s Republic of China (AQSIQ) and the Standardisation Administration of th e People's Republic of China (SAC)
 Contents 
 
Introduction ……………………………………………………………………….. II 1   Scope ………………………………………………………………………… 1 2   Normative references ………………………………………………………… 1 3   Ordering contents …………………………………………………………….. 2 4   Dimensions, shapes and weights …...…..……………………………………. 2 5   Technical requirements ………………………………………………………. 4 6   Test methods …………………………………………………………………. 6 7   Inspection rules ………………………………………………………………. 7 8   Packaging, markings and quality certifications ..……………………………. 7 Introduction  
     This Standard co rresponds to ISO 9329-1: 1989, “ Seamless steel tubes for 
pressure purposes –– Technical delivery condi tions –– Part 1: Una lloyed steels with 
specified room temperature properties” (E nglish version). The c onsistency of this 
Standard with ISO 9329-1: 1989  is non-equivalent. 
As of the implementation date of th is Standard, GB 3087-1999, “Seamless steel 
tubes for low and medium pressure” shall be abolished.  Compared with GB 
3087-1999, the major changes to this Standard are as follows:  
–– the application scope of st eel tubes has been revised; 
–– ordering contents have been increased;  –– the permissible deviation of dimensions has been revised; –– the requirements for full-length curvature have been increased; 
––the requirements for terminal he ad bevelling have been increased; 
–– examples for markings have been deleted; ––the smelting methods of steel have been revised; ––the requirements for delivery conditions  of steel tubes have been revised; 
––the requirements for concrete manufact uring methods of hot expansion steel 
tubes have been increased; ––the requirements for mechanical perf ormance of steel tubes have been 
revised; 
––the judgment rules for the positions of point 6 (bottom) and point 12 (top) of 
test sample in the flattening test of  steel tubes have been increased; 
––the requirements for the edge cu rling test have been deleted; 
––flaw detection has been revised to re place the inspection requirements of the 
hydraulic test. The agreed clauses and recommended data  of this Standard are non-mandatory 
clauses, whilst the rest of the clauses are mandatory. This Standard was proposed by China Iron and Steel Association. 
This Standard is under the ju risdiction of the National Stee l Standardisation Technical 
Committee. 
The units that participated in drafting this Standard are: Angang Steel Co., Ltd., 
and Pangang Group Chengdu Iron and Steel Co., Ltd.  
The main drafters of this Standard ar e: Peng Zhang, Huixuan Zhang, Zhimin Pu, 
and Qi Li. 
This Standard replaces the following pr eviously issued versions of the 
Standard: 
GB3087 -1982 and GB3087-1999. Seamless steel tubes for low and medium pressure boiler  
 
1   Scope 
     This Standard specifies the orderi ng contents, dimensi ons, shapes, weights, 
technical requirements, test methods, inspect ion rules, and requirements for packaging, 
marking and quality certifications of se amless steel tubes for low and medium 
pressure boilers. 
This Standard is applicable to the ma nufacturing of seamless steel tubes of 
quality carbon structural steels for differen t types of low and medium pressure boilers. 
 
2   Normative references 
     The provisions of the following docum ents become provisions of this Standard 
after being referenced. For dated reference documents, all later amendments (excluding corrigenda) and revi sed versions do not apply to  this Standard. However, 
the parties to the agreement are encouraged  to study whether the latest version of 
these documents applies. For undated referen ce documents, the latest versions apply. 
     GB/T 222 Permissible tolerances fo r the chemical composition of steel products 
GB/T 223.3 Methods for chemical anal ysis of iron, steel and alloy - The 
diantipyryl methane phosphomolybdate gravim etric method for the determination of 
phosphorus content 
GB/T 223.5 Methods for chemical anal ysis of iron, steel and alloy - The 
reduced molybdosilicate spectrophotometric method for the determination of acid-soluble silicon content 
GB/T 223.10 Methods for chemical anal ysis of iron, steel  and alloy - The 
cupferron separation-chrome azurol S. phot ometric method for the determination of 
aluminium content 
GB/T 223.12 Methods for chemical anal ysis of iron, steel  and alloy - The 
sodium carbonate separation-diphenyl carbazide photometric method for the 
determination of chromium content 
GB/T 223.18 Methods for chemical anal ysis of iron, steel  and alloy - The 
sodium thiosulfate separation iodimetric  method for the determination of copper 
content 
GB/T 223.19 Methods for chemical analys is of iron, steel and alloy - The 
neocuproine-chloroform extr action photometric method for the determination of 
copper content 
GB/T 223.23 Methods for chemical anal ysis of iron, steel  and alloy - The dimethylglyoxime spectrophotometric method fo r the determination of nickel content 
GB/T 223.24 Methods for chemical anal ysis of iron, steel  and alloy - The 
extraction separation - The dimethylglyoxi me spectrophotometric method for the 
determination of nickel content 
GB/T 223.37 Methods for chemical anal ysis of iron, steel  and alloy - The 
indophenol blue photometric method for the de termination of nitrogen content after 
distillation separation 
GB/T 223.54 Methods for chemical analysis of iron, steel and alloy - The flame 
atomic absorption spectrophotometric method fo r the determination of nickel content 
GB/T 223.58 Methods for chemical anal ysis of iron, steel  and alloy - The 
sodium arsenite-sodium nitrite titrimetric method for the determination of manganese 
content 
GB/T 223.59 Methods for chemical analys is of steel, steel and alloy - The 
reduced molybdoantimonyl phosphoric acid photometric method for the determination of phosphorus content 
GB/T 223.60 Methods for chemical anal ysis of iron, steel  and alloy - The 
perchloric acid dehydration gravimetric method for the determination of silicon 
content 
GB/T 223.61 Methods for chemical anal ysis of iron, steel  and alloy - The 
ammonium phosphomolybdate volumetric method for the determination of 
phosphorus content 
GB/T 223.62 Methods for chemical analysis  of iron, steel and alloy - The butyl 
acetate extraction photometric method for the determination of phosphorus content 
GB/T 223.63 Methods for chemical anal ysis of iron, steel  and alloy - The 
sodium (potassium) periodate photomet ric method for the determination of 
manganese content 
GB/T 223.64 Methods for chemical analysis of iron, steel and alloy - The flame 
atomic absorption spectrometric method for the determination of manganese content 
GB/T 223.68 Methods for chemical anal ysis of iron, steel  and alloy - The 
potassium iodate titration method after combustion in the pipe furnace for the 
determination of sulphur content 
GB/T 223.69 Methods for chemical analys is of iron, steel and alloy  - The 
gas-volumetric method after combustion in th e pipe furnace for the determination of 
carbon content  
GB/T 223.71 Methods for chemical anal ysis of iron, steel  and alloy - The 
gravimetric method after combustion in th e pipe furnace for the determination of 
carbon content 
GB/T 223.72 Methods for chemical anal ysis of iron, steel  and alloy - The alumina chromatographic separation - Bari um sulphate gravimetric method for the 
determination of sulphur content 
GB/T 223.74 Methods for chemical anal ysis of iron, steel  and alloy - The 
combustion gravimetric/gas-volumetric met hod for the determination of combined 
carbon content 
GB/T 226 Etch test for macrostr ucture and defect of steels 
GB/T 228 Metallic materials - Tensile testing at ambient temperature (GB/T 
228-2002, eqv. ISO 6892: 1998) 
GB/T 241 Metal tubes - Hydros tatic pressure testing  
GB/T 242 Metal tubes - Drift expa nding test (GB/T 242-2007, ISO 8493: 1998: 
IDT) 
GB/T 244 Metallic materials  -  Tubes  -  Bend test GB/T 244-1997, eqv. ISO 
8491: 1986) 
GB/T 246 Metallic materials - Tubes - Flattening test (GB/T 246-2007, ISO 
8492: 1998, IDT) 
GB/T 699 Quality carbon structure steels GB/T 1979 Diagram of a Low Magnifi cation Texture Blemish Grading of 
Structural Steel 
GB/T 2102 Acceptance, packing, marking a nd quality certification of steel pipe 
GB/T 2975 Steel and steel products - Locati on and preparation of  test pieces for 
mechanical testing (GB/T 2975-1998, eqv. ISO 377: 1997)    
GB/T 4336 Standard test method for spark discharge atomic emission 
spectrometric analysis of carbon a nd low-Alloy steel (Routine method) 
GB/T 4338 Metallic materials - Tensile te sting at elevated temperature (GB/T 
4338-2006, ISO 783: 1999, MOD) 
GB/T 5777-1996 Seamless steel tubes - Me thods for ultrasonic testing (eqv. 
ISO 9303: 1989) 
GB/T 7735 Steel tubes - The inspecti on method on eddy current test (GB/T 
7735-2004, ISO 9304: 1989, MOD) 
GB/T 12606 Steel tubes - The testing method of magnetic flux leakage (GB/T 
12606, eqv. ISO 9402: 1989, ISO 9598: 1989) 
GB/T 17395 Dimensions, shapes, masses a nd tolerances of seamless steel tubes 
(GB/T 17395-XXXX, neq. ISO 1127: 1992, ISO 4200: 1991, ISO 5252: 1991) 
GB/T 20066 Steel and iron - Sampling and preparation of samples for the 
determination of chemical composition (GB/T 20066-2006, ISO 14284: 1996, IDT) 
GB/T 20123 Steel and iron - Determination of total carbon and sulphur content  
- Infrared absorption method after combus tion in an induction furnace (Routine method) (GB/T 20123-2006, ISO 15350: 2000, IDT) 
GB/T 20124 Steel and iron  -  Determination of nitrogen content  -  Thermal 
conductimetric method after fusion in a curr ent of inert gas (Routine method) (GB/T 
20124-2006, ISO 15351: 1999, IDT)  
3   Ordering contents 
     The agreements or orders for steel tubes purchased in accordance with this 
Standard should include but not be limited to the following contents: 
a) Standard numbers; b) Product name; c) Steel numbers; d) Ordering quantity (total weight or total length); 
e) Delivery condition; f) Dimensions and specifications; g) Special requirements. 
 
4   Dimensions, shapes and weights 
4.1.   Outer diameter and wall thickness 
4.1.1   The outer diameter (D) and wall thic kness (S) of steel tubes should meet the 
requirements set out in GB/T 17395. 4.1.2   According to the demanding party' s request, which is then negotiated 
between the supplying and demanding parties,  the other outer di ameters and wall 
thickness of other steel tubes can be provided. 
4.2   Permissible deviation of ou ter diameter and wall thickness 
4.2.1   The permissible deviation of the outer diameter of steel tubes should meet the 
requirements set out in Table 1. 
Table 1   Permissible deviation of  outer diameter of steel tubes
   Unit: mm  
Type of steel tube Permissible deviation 
Hot rolled (extruded, expanded) steel tube ± 1.0% D or ± 0.50, take the greater number 
Cold drawn (rolled) steel tube ± 1.0% D or ± 0.30, take the greater number 
4.2.2 The permissible deviation of the wall  thickness of hot rolled (extrusion, 
expansion) steel tubes should meet the requireme nts set out in Table 2. 
4.2.3 The permissible deviation of the wall thickness of cold drawn (rolled) steel 
tubes should meet the requirements set forth in Table 3. 4.2.4 According to the demanding party’s requ est, which is then negotiated between 
the supplying and demanding parties and in dicated in the agreement, steel tubes 
beyond the permissible deviation of dimensi ons shown in Table 1, Table 2 and Table 3 may be produced. 
 
Table 2   Permissible deviation of the wall thickness of hot rolled  
(extrusion, expansion) steel tubes             Unit: mm  
Type of steel 
tube Outer diameter 
of steel tube S / D Permissible deviation 
≤ 102 – ± 12.5 % S or ± 0.40, take the greater number 
≤ 0.05 ± 15% S or ± 0.40, take the greater number 
> 0.05 ~ 0.10 ± 12.5% S or ± 0.40, take the greater number Hot rolled 
(extruded) 
steel tube > 102 
> 0.10 + 12.5% S 
- 10% S 
Hot expanded 
steel tube + 15% S 
 
Table 3   Permissible deviation of the wall thickness of cold drawn (rolled) steel  
tubes                        Unit: mm  
Type of steel tube Wall thickness Permissible deviation 
+15 ≤ 3 - 10 % S or ± 0.15, take the greater number  
Cold drawn (rolled) steel tube 
> 3 + 12.5% S 
- 10% S 
 
4.3   Length 
4.3.1   General length  
The general length of steel tubes is 4000 mm ~ 12500 mm. After negotiation 
between the supplying and demanding parties, a nd as indicated in the agreement, steel 
tubes with a length greater th an 12500 mm may be delivered. 
4.3.2   Cut length and multiple length 
According to the demanding party's request, and as indicated in the agreement, 
steel tubes can be delivered according to the cut length or multiple length. The cut 
length of steel tube should be within the range of the general length. The permissible 
deviation of the full length should meet the following requirements: 
a) Cut length ≤ 6000 mm, 0~10 mm; 
b) Cut length > 6000 mm, 0~ 15mm. The total multiple lengths of steel tube s should be within the range of the 
general length. The permissible deviation of full length is:  
+20 
0 mm. 
Each multiple length should leave a cut margin according to the following 
requirements:      a) When outer diameter is ≤ 159 mm, cut margin is 5 mm ~ 10 mm; 
     b) When outer diameter is > 159 mm, cut margin is 10 mm ~ 15 mm 
4.4   Curvature 
4.4.1   The curvature for each metre of stee l tube should meet the requirements set 
out in Table 4. 
Table 4   Curvature for each metre of steel tube 
Nominal wall thickness, mm Curvature per metre, mm/m 
≤ 15 ≤ 1.5 
> 15 ~ 30 ≤ 2.0 
> 30 or outer diameter ≥ 351 ≤ 3.0 
 
4.4.2  The full-length curvature of the steel tube  should not be greater than 1.5% of the 
total length of the steel tube, and its full-le ngth bending should not be greater than 12 
mm. 
4.5   Non-circularity and wall thickness unevenness 
     According to the demanding party’s request, which is then negotiated between 
the supplying and demanding parties and indicated in the agreement, the non-circularity and wall thickness unevenness of steel tubes should not exceed 80% of 
the tolerances for outer diameter and wall thickness respectively. 
4.6   Shape of terminal head 
     The terminal surfaces at the two ends of a steel tube should cut straight with the 
axis of the steel tube. The burrs at the cuts should be cleared. The terminal parts of the 
steel tube should be bevelled (see Fi gure 1), and should meet the following 
requirements:      a) When the outer diameter of steel tube is not greater than 60 mm, the 
bevelling should not exceed 1.5mm;      b) When the outer diameter of steel  tube is greater than 60 mm, the bevelling 
should not exceed 2.5% of the outer diam eter of steel tube, but the maximum 
bevelling should not exceed 6 mm.                                                  B e v e l l i n g   
Figure 1   Bevelling 
4.7   Delivery weight 
4.7.1   Steel tubes are delivered according to  their actual weight. They can also be delivered according to theoretical weight. The theoretical weight of the steel tube 
should be calculated in accordance with the requirements of GB/T 17395. The density 
of steel is taken as 7.85 kg/dm3. 
4.7.2   According to the demanding part y’s request, which is then negotiated 
between the supplying and demanding parties and indicated in the agreement, the 
deviation between the theoretical weight and actual weight of the steel tube to be 
delivered should meet the following requirements:      a )  S i n g l e  s t e e l  t u b e s :   ±  1 0 % ;       b) Steel tubes with each batch at minimum of 10 tonnes: ± 7.5%.  
5   Technical requirements 
5.1   Number and chemical composition of steel 
5.1.1   Steel tubes are made with steel No 10 and No 20. 
5.1.2   The chemical composition (smelting an alysis) of steel tubes should meet the 
requirements set out in GB/T 699. 5.1.3   If the demanding party requests an an alysis of the fini shed product, this 
request should be indicated in the agre ement. The permissible deviation for the 
chemical composition of finished steel tube products should meet the requirements set 
out in GB/T 222. 
5.2   Methods for making tubes 
5.2.1   Smelting method of steel  
     Steel making should adopt elect ric furnace and out-of-furnace smelting, or 
oxygen converter and out-of-furnace sme lting. After negotiation between the 
supplying and demanding parties, a smelti ng method with other higher requirements 
may also be adopted. If the demanding party designates a certain smelting method, 
this should be indicated in the agreement. 
5.2.2   Method for making tube billets 
     Tube billets are made by adopting th e continuous casting or hot rolling (forging) 
method. Steel ingots can also be dire ctly used for making tube billets. 
5.2.3   Making method of steel tubes 
     Steel tubes should be made by usi ng the hot rolled (ext rusion, expansion) or 
cold drawn (rolled) seamless method. If th e demanding party designates a certain 
method for making the tubes, this should be indicated in the agreement. Steel tubes 
made by hot expansion refer to  steel tubes of larger di ameter formed by expansion 
and deformation after billet steel tubes are overall heated. 
5.3   Delivery condition 
5.3.1   When hot rolled (extrusion, expans ion) steel tubes ar e delivered under hot 
rolling or normalising condition, the finish ing rolling temperature of the delivered steel tubes under hot rolling conditions should not be lowe r than the phase-transition 
critical temperature A r3. 
     According to the demanding party’s request, which is then negotiated between 
the supplying and demanding parties and in dicated in the agreement, hot rolled 
(extrusion, expansion) steel tubes can be  delivered under norma lising conditions.  
When the finishing rolling temperature of hot  expansion steel tubes is not lower than 
the phase-transition critical temperature A r3, and after the steel tubes have undergone 
air-cooling, the steel tubes are thought  to have gone through normalising. 
5.3.2 Cold drawn (rolled) steel tubes should be delivered under normalising conditions. 
5.4   Mechanical performance 
5.4.1   The longitudinal mechanical perf ormance of steel tubes under delivery 
conditions should meet the requi rements set out in Table 5. 
Table 5   Mechanics performance of steel tubes 
Lower yield strength ReL, MPa  
Wall thickness, mm 
≤ 16 > 16 Elongation 
percentage 
after breaking 
A 
 % Serial No Steel No Tensile 
strength 
Rm 
MPa No less than No less than 
1 10 335~475 205 195 24 
2 20 410~550 245 235 20 
 
5.4.2  When the demanding party indicates in th e agreement that the steel tube is to 
be used as the overheat steam tube of a medium-pressure boiler, the supply party 
should guarantee that th e specified non-proportiona l elongation strength ( Rp0.2) of the 
steel tube under high temperatures meets the require ments set out in Table 6. The 
supplying party is not permitted to carry out an inspection of this.      According to the demanding party's request, which is then negotiated between 
the supplying and demanding parties and meet s the test temperature indicated in the 
agreement, steel tubes can undergo the hi gh-temperature tensile test. The high 
temperature specified non-propo rtional elongation strength ( R
p0.2) under the 
corresponding temperature should meet th e requirements set out in Table 6. 
Table 6   Minimum value of specified no n-proportional elongation strength of 
steel tube under high temperature 
Minimum value of specified non-proportional elongation strength   
Rp0.2 , MPa 
Test temperature, o C Steel No Test 
condition 
200 250 300 350 400 450 
10 Supply 165 145 122 111 109 107 20 condition 188 170 149 137 134 132 
 
5.5   Technical performance 
5.5.1   Flattening test  
      Steel tubes with an outer diam eter greater than 22 mm and up to 400 mm, and 
wall thickness greater than 10 mm should undergo the flattening test. After the 
samples are flattened, the distance  H between two plates should be calculated 
according to formula (1):                            ( 1  +  α ) S 
H = --------------------  …………..………………………… (1) 
     α + S / D 
     I n  t h e  f o r m u l a :       H –– distance between plates, in mm; 
S –– nominal wall thickness of steel tube, in mm; 
D –– nominal outer diameter of steel tube, in mm; 
α –– deformation coefficient of unit length, taking α = 0.08; when S/D ≥ 0.1, 
taking α = 0.07. 
After flattening, no fissures or cracks are permitted to appear on the sample. The following circumstance should be referential for judging whether the 
flattening test is passed or not: 
When S/D > 0.1, the point 6 (bottom) and point  12 (top) positions of sample are 
situated at the cracks on the inner surface. 
5.5.2  Drift expansion test 
     According to the demanding party’s request, which is then negotiated between 
the supplying and demanding parties and indica ted in the agreement, steel tubes with 
wall thickness no greater than 8 mm can undergo the drift expansion test. The drift expansion test is performed for one of the tip tapers being 30
o, 45o or 60o. The drift 
expansion rate of the outer diameter of th e sample after drift expansion should meet 
the requirements set out in Table 7. After drift expansion, no fi ssures or cracks are 
permitted to appear on the sample. 
Table 7   Drift expansion rate of outer diameter of sample 
Expansion value of outer diameter of steel tube, % 
Inner diameter / Outer diameter Steel No 
≤ 0.6 > 0.6 ~ 0.8 > 0.8 
10 12 15 19 
20 10 12 17 
 
5.5.3  Bending test      Steel tubes with an outer diameter  not greater than 22 mm should undergo the 
bending test. The bending angle is 90o. The bending radius is 6 times the outer 
diameter of the steel tube. After bendi ng the sample, no fissures or cracks are 
permitted to appear on the sample. 
P = 2SR / D  ………………………………….. (2) 
     I n  t h e  f o r m u l a :  
P –– test pressure, in MPa; 
S –– nominal wall thickness of steel tube, in mm; 
D –– nominal outer diameter of steel tube, in mm; 
R –– permissible stress, being 60% of lowe r yield strength speci fied in Table 5, 
in MPa. 
The supplying party can use eddy current flaw detection, magnetic leakage flaw 
detection or ultrasonic flaw  detection instead of the hydr aulic test. If the demanding 
party requests an ultrasonic inspection, the supplying party s hould replace the 
hydraulic test with an ultrasonic inspecti on. During the eddy current flaw detection 
test, the manual defect of the reference samp le tube should meet the requirements set 
out in post-inspection acceptance grade A specified in GB/T 7735. During the 
magnetic leakage flaw detection test, th e longitudinal manual defect on the outer 
surface of the reference sample tube should meet the requirements for post-inspection 
acceptance grade L4 specified in GB/T 12606. During ultrasonic flaw detection, the 
longitudinal manual defect on the outer surf ace of reference sample tube should meet 
the requirements for post-inspection accep tance grade C12 specified in GB/T 
5777-1996. 
5.7   Macroscopic examination 
     For steel tubes directly made by c ontinuously cast billets or steel ingots, the 
supplying party should guarantee that there are no wh ite spots, impurities, sub-surface 
air bubbles, skull patches or layering on the cross-sectional acid pickled macroscopic 
tissue of the billet  or steel tube. 
5.8   Surface quality 
     No fissures, folding, scabs, rolling cr eases or separation layers should be visible 
on the inner and outer surfaces of the steel tube. Such defects should be completely 
eradicated. The removal depth should not exceed 10% of nominal wall thickness.  
The actual wall thickness at the clearing place should not be smaller than the 
minimum value of permissible deviation of wall thickness.      The permissible depth of straight tubes should meet the following requirements: 
     a) Cold drawn (rolled) steel tube: No greater than 4% of wall thickness, and the maximum depth is 0.3 mm;      b) Hot rolled (extrusion, expansion) steel tube: No greater  than 5% of wall thickness, and the maximum depth is 0.5 mm. 
     Other partial defects are permitted, provided they do not exceed the negative deviation of wall thickness. 
5.9   Non-destructive inspection 
     According to the demanding party’s request, which is then negotiated between 
the supplying and demanding parties and indica ted in the agreement, ultrasonic flaw 
detection may be individually performed for steel tubes. The longitudinal manual 
defect of the referen ce sample tube should meet the re quirements for post-inspection 
acceptance grade C8 specified in GB/T 5777-1996.  
6   Test methods 
6.1   The dimensions and shapes of steel  tubes should adopt the measuring method 
that meets the accuracy requirements for carrying out the measurement. 6.2   The inner and outer surfaces of the steel tube should undergo individual visual 
inspection in a well-lit environment. 6.3   Other inspections of steel tubes shoul d meet the requirements set out in Table 
8. 
Table 8   Inspection items, number of  samples, sampling methods and test 
methods of steel tubes 
Serial 
No Inspection item Number of samples Sampling 
method Test method 
1 Chemical 
composition Take one sample respectively from 
each furnace GB/T 20066 GB/T 223 
GB/T 4336 
2 Tensile test Take one sample respectively from 
two steel tubes out of each batch GB/T 2975 GB/T 228 
3 High-temperature 
tensile test Take one sample respectively from 
two steel tubes out of each batch GB/T 2975 GB/T 4338 
4 Flattening test Take one sample respectively from 
two steel tubes out of each batch GB/T 2975 GB/T 246 
5 Drift expansion test Take one sample respectively from 
two steel tubes out of each batch GB/T 2975 GB/T 242 
6 Bending test Take one sample respectively from 
two steel tubes out of each batch GB/T 2975 GB/T 244 
7 Hydraulic test Tube by tube –– GB/T 241 
8 Eddy current flaw 
detection Tube by tube –– GB/T 7735 
9 Magnetic leakage 
flaw detection Tube by tube –– GB/T 12606 10 Ultrasonic flaw 
detection Tube by tube –– GB/T 5777 
11 Macroscopic 
examination Take one sample respectively from 
two steel tubes out of each batch GB/T226 GB/T 226 
GB/T 1979 
 
7   Inspection rules 
7.1   Inspection and acceptance 
     The quality technical supervisory department of the supplying party performs 
the inspection and acceptance of steel tubes. 
7.2   Batching rules 
7.2.1   The inspection and acceptance of st eel tubes is performed batch by batch. 
7.2.2   If the steel tubes have been cut to  single tubes and do not carry out heat 
treatment, every tube section cut from the st eel tube rolled from a tube billet can be 
regarded as a tube. 7.2.3   Each batch should be composed of steel tubes of the same steel number, the 
same furnace number, the same specifications  and the same heat treatment system 
(heat). The quantity of steel tubes in each batch should not exceed the following 
requirements:      a) Those with outer diameter not greater than 76 mm and wall thickness not 
greater than 3 mm : 400 steel tubes; 
     b) Those with outer diameter  greater than 351 mm : 50 steel tubes; 
     c) Those with other dimensions: 200 steel tubes.      With regard to the quantity of other steel tubes, if it is not less than 50% of the 
above specified quantity, the steel tubes ar e independently regarded as a batch; 
however, if it is less than 50%  of the above specified quantity, the steel tubes can be 
included in a similar batch with the same steel number, the same furnace number, the same specifications and the same heat treatment system (heat). 
7.3   Number of samples 
     The number of samples to be taken from each batch to undergo performance 
inspection should meet the requi rements set out in Table 8. 
7.4   Re-inspection and judgment rules 
     The re-inspection and judgment rules of steel tubes should meet the 
requirements of GB/T 2102.  
8   Packaging, markings and quality certifications 
     The packaging, markings and quality certifications of st eel tubes should meet 
the requirements of GB/T 2102.  _____________________