API Welding 1

[nadfourchon]

In API 16A Sec. 7.3.6.2 "Deposited weld metal properties" it states: The deposited weld metal mechanical properties shall meet or exceed the min specified mechanical properties of the base material. Verification of properties shall be established through the implementation of the manufacturer's WPS and supporting PQR. When materials of differing strength are joined, the weld metal shall meet the minimum requirements of the lesser material.

What does this mean? Does this say that when I develop a new WPS and PQR that I must do mechanical testing with specimens made from strictly weld metal along with the specimens of base and weld metal? Or is the required mechanical testing of the welded specimens enough?

 

[metengr]

What this means is mechanical testing of specific weld coupons as described in ASME Section IX.

 

[nadfourchon]

Not sure if I understand. Are you saying that the coupons are made with just the weld metal or the weld metal with the two adjoining base materials? I have mechanical test results from specimens of the two pieces welded together weld metal included.
Were can I find the this info in Sec IX?

New to this type of problem, please bare with me.

 

[metengr]

The coupon consists of weld metal and adjoining base metals. All of this can be found in the ASME Boiler and Pressure Vessel Code , Section IX Welding and Brazing Guidelines.

 

[nadfourchon]

Thanks

 

[ndeguy]

"The deposited weld metal mechanical properties shall meet or exceed the min specified mechanical properties of the base material."

This means that for the PQR transvere tensile, if the fracture occurs in the base material at a stress greater than the specified requirements of the base metal then the requirements of 7.3.6.2. have been demonstrated. Of course hardness and impact strengths also should be considered.

Nigel Armstrong
Lloyds Register
Independent Verification Body Surveyor

 

[roadapple]

If you are having to deal with API welding then I sympathize with you.

My welding experience in API 6A was such that I worked day and night to eliminate it (mostly) from all our designs.

IMHO there are few if any materials listed in ASME that will get you the strength you will need - but we didn't do any work with 16A. Most of our stuff was 100k yield and up.

Transverse tensiles will answer the question as ndeguy pointed out. If you are using unrecognized grades such as 4140 (in its various forms) pay particular attention to the heat treatment on the MTR. Review as many sample MTR's as you can to try to nail down the "most common" temper temperature - API will only allow +/- 25F of deviation on the PWSR. So, if you stress relieve at too high a temperature you will be hosed if you material comes in with a temper temperature close to that range. For your PQR-try incrementally increasing your PWSR temperature until meet your mechanicals - that way you can have a lower PWSR temperature than the majority of your typical material shipments.

Sorry for the long post - but I wanted to help.

roadapple