SA 234 Grade WPB Elbow - Tensile Requirements

[Quality2479]

Good Day Everyone!!!!

Material Description - SA234 Gr.WPB, Hot formed between 780-980 Degree Celcius
In MTC it has been mentioned as the Tensile test (Mechanical Properties) carried out on Raw Material.

As per SA 234 Tensile requirements Cl.9.0 (9.1 to 9.4), I am bit confused and would like to know whether the Tensile test coupon to be taken from the Finished fittings or from the Raw Material used to manufacture the fittings.

Thanks in advance for reply.

 

[metengr]

Here is what 9.4 states in SA-234 regarding tensile test results and what they mean

9.4 Records of the tension tests shall be certification
that the material of the fitting meets the tensile requirements
of this specification provided the heat treatments are the
same. If the raw material was not tested, or the fitting is
not in the same condition of heat treatment, the fitting
manufacturer shall perform the required test on material
representative of the finished fitting from each heat of
starting material.

So, you need to determine what heat treatment was performed on the raw material so that the tensile test results represent the material condition of the finished fitting. For example see below after hot working,

7.2 Hot-formed WPB, WPC, and WPR fittings
upon which the final forming operation is completed at
a temperature above 1150°F [620°C] and below 1800°F
[980°C] need not be heat treated provided they are cooled
in still air.

 

[Quality2479]

Good Day!!!!

Thanks Sir for your reply.

Most of the MTCs we have reviewed it mentions only the Starting material (Pipe, Bar or Plate), it doesn't mention the condition of Raw Material used to manufacture the fittings as it is not an requirement to mention in the MTC as per SA234 Cl.17.0 Certification.

MTC only gives a detail of final product (Fittings) Hot forming temperature details or Heat treatment Temperature and Time details if Heat treated.

In this case we might have to ask an clarification to the mill regarding the forming temperature of raw material used to manufacture the fittings.

Could you please let me know whether my understanding is correct.

From your above reply we understand that the tensile test coupon to be taken from the raw material and not from the fittings.

 

[metengr]

Yes, your understanding is correct. You need to know the heat treatment condition, if any, of the raw material used to manufacture the fittings. For example, if the raw material was annealed or cooled in air after forming and the material is hot worked and cooled in air for the WPB fitting, tensile properties of the raw material would be acceptable. If the raw material was annealed or cooled in air, and now the material is subjected to a quench and temper heat treatment, this would require tensile testing of the final heat treated fitting.

 

[MatSci1254]

Hi,

I have plate MTC which is S275JR+N, N I guess stands for Normalizing. Fitting made out of these plate are certified to SA234 WPBW and all are hot formed between 780-980 Degree C and in some cases these fitting are stress relived (Above 19mm as required by B31.3).

Manufacturer has performed tensile test on specimen taken from plate. As I understand from Clause 9.4 of SA234, specimen shall be in same condition of heat treatment as of finished fitting, but in this case fitting are hot formed or stress relived (n case of thickness is above 19mm) and specimen tested is in normalized condition.

Is it correct? I think it is not. if it is not could someone please advise what treatment can be imparted to specimen from plate.

Would appreciate you comment.

Regards
MS


Regards
MatSci1254

 

[metengr]

The manufacturer should run a coupon of the original plate material at the same temperature as hot forming and cooling for the fittings to evaluate mechanical properties.

 

[MatSci1254]

Do you mean manufacturer shall heat plate sample to a temp between 780-980 Deg C and cool in still air and then subject those sample to mechanical testing. will it not be a repeat of normalizization which has been done already on the plate by plate manufacturer?

one of answer i got is that the stress relliveing does not alter the mehcnial properties and since the fitting are normalized formed therefore it is in same condition of heat treatment as of the plate and hence test on fittings are not required, the test conducted on plate sample are representative of the fitting propeties.

Regards
MatSci1254

 

[metengr]

You have to evaluate if the original normalization temperature for the plate was higher than the hot working temperature being done for the fittings. Hot working is not the same as a normalizing heat treatment. Stress relief treatment is exempt because you are not altering the bulk properties.