Charpy impact testing requirements

[engr2GW]

Hi,

when the anticipated temperature (ambience or media) in an oil and gas facility is not going to go below -20F is Charpy impact testing required for the weld procedure?
1. For API wellhead welding to ANSI line pipe, MDT above at -20F
2. Same as 1 above but MDT below -20F
3. B31.3, 31.4, or 31.8 piping with MDT above -20F
4. Same as 3 above with MDT below -20F

I am under the impression from my little knowlege of the code that impact testing is required only for 2 and 4 above, is that right?

If so, how does one determine the test temperature?

Thanks a lot.

 

[vesselfab]

depends on thickness and material of the unit.

that -20 rule will get you in trouble.

 

[engr2GW]

The thickness of the pipes we use range from 0.2" and upto 0.75" and sometimes up to 1". Materials are mostly A106 grade B class. some A106 grade C, grade A, API 5L X-42, 46, and X-52. And also AISI 4130 for wellhead flange to be welded to A106 pipe.

Can you please expand on getting into trouble with the -20F rule

 

[vesselfab]

Thick Cr-Mo pipe and flanges

 

[weldtek]

mysarah,
For me, the problem with your question is that it covers too much ground. As I'm sure you know, impact testing requirements are driven by the construction code and you've referenced several of them. In addition material types and thicknesses all influence impact testing requirements and you've given several of those. I think you can be pretty sure that 4130 material will not be exempt though.

 

[engr2GW]

@weldtek,
let me narrow it down.
1. Most of the line pipe welding are between A106B to the same, will this require Charpy for temperature below -20F for that base metal thickness range, considering only ASME B31.3?
2. What about 4130 to A106B for 0.1875" to 1.2" thickness, B31.3 too?
3. Finally, 4130 to the same for the same, API SPEC 6A?

Thanks Weldtek

 

[weldtek]

mysarah,
So if I understand correctly we can condense your question to two materials A106B & 4130, and one code B31.3.
Per B31.3 A106B is exempt from impact testing at -20F for thicknesses up to 1/2". This comes from Table A1 showing A106B as a Curve B material and referencing Table 323.2.2A for temperature / thickness exemptions. For non exempt materials review Table 323.2.2 for testing requirements.
Be sure to use consumables that are qualified by the manufacturer to -20 F or lower.
I didn't spend a lot of time but was unable to locate 4130 listed in Table A1 under several of the common material specifications. if you know the material specification eg A322 or other, provide that and I'll look again.
If the material is unlisted it'll require testing.

 

[SJones]

For the API 6A material, it depends on the PSL Level and Temperature Classification. Essentially, if the material has been impact tested, so must the welding procedure qualification test weld. The number of sets of impact tests just goes up with PSL level.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[engr2GW]

@ Weldtek and SJones,

Thanks a lot for your responses.
What I'm understanding is: For the A106 (P1 to P1, the test is not required for -20F and above), but required for below -20F.

2. If the weld is between API 4130 material and ANSI pipe (A106B), since the weld design is governed by the weaker material (A106B), do I still need to worry about charpy, because the tensile, pressure rating, etc are based on the waeker material.

3. Finally, for the API SPEC 6A application, i.e. 4130 to 4130, does anyone know where in the code that I can find a decision making requirement if I need Charp on those, BTW, they are ordered PSL 1 and the MDT is not below -20F

Thanks a lot.

 

[vesselfab]

don't forget that your weld consumables must be certified for -20F

some are not

 

[stanweld]

mysarah,
You are incorrect. Under B31.3, API 5L & 5LX follow Curve A in Fig. 323.2.2A unless normalized or quenched and tempered. A-106 follows Curve B; impact testing will be required at temperatures > -20 F depending on thickness.

 

[engr2GW]

Thanks Stanweld,

I'm still trying to understand the table and curves completely. But here's a way I can simplify it.

1. For materials X-42, X-46, X-52, A106 grade A, B, and C. for thickness ranges 0.1875" - 1", will welding any combination of the above for services of -20 and higher require charpy on the WPS for thickness upto 0.5", what about thickness higher than that, does that mean charpy will be required even for temperature higher than -20F. this question is per Table/figure 323.2.2A in B31.3

2. What about 4130 to any of the above materials for the same question

3. Finally 4130 to the same?

Thank you.

 

[weldtek]

mysarah,
I think you need to be careful with generalizing. As stanweld points out the API 5L materials fall under a different curve than the 106B. Curve A materials require impact testing at -20F at any thickness. As mentioned earlier 106B is exempt to 1/2" wall thickness but thicker schedules are not.
To my knowledge, 4130 isn't listed and therefore not exempt. Dissimilar welds require at least the HAZ to be tested for non exempt materials.

 

[engr2GW]

from B31.3 table and Fig 323.2.2, it appears Charpy is required above 0.5" for A106B. Now I have 7 procedures qualified without Charpy impact testing with TIG, MIG, STICK, and instead of re-welding each coupon and testing them individually, I was thinking about taking the worst case scenarios:
1. 6010 and 7010 worst impact values (but good for -20F though)
2. 1" coupon the highest thickness I use and the one with the highest MDT meaning the worst case per thickness
3. No Post Weld Heat Treatment since PWHT increase impact properties
4. Althogh in curve B of Fig 323.2.2A, 1" has an MDT of 33F, I plan to test it at -20F (worst case)

if the above passes the Charpy, then I can write a verbage that indicates that the better conditions are good, also, most of our stuff are below 0.5" anyway.

Is this a fair idea? should I just do the Charpy on every coupon I welded...Please advice

Thank you.

As much as possible, do it right the first time...

 

[Duwe6]

To have an Impact-Tested WPS, you have to actually test that WPS. Charpy each of your coupons.

 

[REGRUMBLE]

To get back to your original post you mentioned that the ambient temperature is expected to go below -20. The testing must be done at the worst case. Most of our procedures for oil facilities are tested at -35C and for the more northern facilites at -50C. Before you waste time and money on procedures that are worthless. Find out form the customer what is the required temperature. By code this is a contract requirement.

 

[engr2GW]

Actually, I take that back, it's -20F or above, usually not less than 0F.

As much as possible, do it right the first time...

 

[engr2GW]

But again, on a more closer look, it looks like Figure 323.2.2A and table 323.2.2A are talking about material, not welding. The only mention of welding (base metal, HAZ, and weld metal) in B31.3 is in table 323.2.2 and it says for weld, the test should only be if MDT is below -20F. So technically, it sounds more like a material purchasing issue and not a welding issue, in other words, it looks like the welding of A106B material only requires Charpy if MDT is below -20, but the manufacture of the material makes Charpy depend on thickness...

Does that make sense or am I reading it wrong.

As much as possible, do it right the first time...

 

[jbeckhou]

welding 4130 x 4130 PSL-1, -20F (-29c) doesn't require Charpy V-Notch testing. PSL-2 and above require impact testing at or below -20F. See table 7, page 36 API-6A 20th ed.

API allows the manufacturer to establish a P-number grouging for materials not lited in ASME, section 9. See section 6, API-6A.


What type of equipment are you making? Spacer Spool?

Petrotrim Services

http://www.petrotrim.com

 

[stanweld]

engr2GW
API 5LX and A106 B fall under Curve A and B of Fig. 323.2.2A per Table A-1 respectively. As result the requirements of B3 in Table 323.2.2 apply to impact testing of the deposited weld metal and HAZ.