Material with Impact Property Requirements 1

[hamidun]

Dear All,

I have read in this forum that if We have a WPS with same P-NO. material but different Gr. No., We can use the same WPS for that different Gr. No. material when the different Gr. No. material does not have impact property requirements.

My question is how to know whether a material is required to have impact property or not. Because I could not find a material with impact property requirements.
Or do we decide whether a material is required to have impact property or not by knowing the maximum operation temperature of the material used? For example, if the operating temperature exceeds the capability of the material (in this case at low temperature), we need to do impact test for the material, so that we know impact property for that material and after that we need to make a new WPS for that material.

Please help, thank you.

 

[weldstan]

The MDMT is determined by the Design Engineer or Owner. If the MDMT is low, the Construction Code provides the requirements for impact testing and provides materials for use.

If your design is outside of any Code, the Design Engineer should determine the materials and any need for impact testing. Hopefully the Designer should include a Metallurgist/Materials Engineer highly familiar with mechanical metallurgy to determine toughness requirements at operating conditions.

 

[hamidun]

weldstan,

What do you mean by Construction Code?
So, you are saying that the impact property of a material depends on the MDMT?

My understanding about impact property requirements is just like tensile requirements. For example in ASTM A 36, it is clearly stated about tensile requirements of the material. But for impact property requirements, I could not find a material with "impact property requirements".
So, back to my question how to know whether a material is required to have impact property or not. I am so sorry, I am still confused about this.

 

[weldstan]

The construction code may be ASME VIII or ASME B31.3 as examples. In ASME Section II and the Tables in B31.3, for example, can be found materials which are tested for impact toughness like A-350 and A-333 or others. One can add impact test requirements for other materials (like A-36) as well based on MDMT or other service related reasons or material thickness/geometry.

Selection of materials and impact testing of them is a complex subject and I suggest that you review some Mechanical Metallurgy texts for better understanding.

 

[212197]

hamidun (Mechanical) (OP)

U need to read UCS 66 of ASME sec. VIII DIV 1,

In addition to MDMT, thickness of material in question is also a criteria.

 

[hamidun]

weldstan,

Alright, there are material specifications which include impact temperature requirement.

212197,

Thanks for the guidance!

So, if I have a WPS for A 573 Gr. 70 plate which is P-No.1 Gr. No.2, I can use it for A 36 plate (in which it is classified as P-No.1 Gr. No.1) or vice versa, right? Because there is no impact test requirement for A 36 plate and operating temperature is 70-90 deg C.

 

[weldstan]

Not if the PQR is impact tested. Group number is a supplementary essential variable per ASM IX. With those operating conditions why require impact testing or have you a low temp MDMT or high loads relative to yield strength?

If the design materials and welds do not require impact testing, The PQR using A-573 with impact testing will permit welding the A-36 and the A573 amongst many other Group 1 and Group 2 materials.

 

[hamidun]

weldstan,

What do you mean by "Not if the PQR is impact tested."?

So, In my case stated above, the WPS for A 573 Gr. 70 plate can be used for A 36 plate, right?

 

[weldstan]

Yes, as long as the A-36 does not require impact testing.

 

[hamidun]

weldstan,

Alright, I understand why you said "Not if the PQR is impact tested." If the PQR of A 573 Gr. 70 plate is already impact tested, then it is certain that WPS of A 573 Gr. 70 can be used for A 36 plate.

But If the PQR of A 573 Gr. 70 is not impact tested and I want to use for A 36 (which does not need impact test as well), it is not a problem, right?

Just want to make sure...

 

[weldstan]

Correct.

 

[hamidun]

Thanks for the help weldstan!