SA 516 Grade 70 Welded with Stainless Steel 316L

If PWHT is required for A516 Gr. 70 welds to itself, then you will need them for this dissimilar weld, not for any reason concerning the dissimilar weld metal but because the HAZ on the A516 parent metal will need annealing. I do not recall off the top of my head if Gr. 70 requires PWHT, Seems like I remember that it does, I know Gr 50 does not.

Dear sir,

Thanks for your reply but could you please add some more details.

Thank you,

Ilangkumaran

A 50 mm thk plate of SA-516 Gr. 70 will require PWHT if welded with itself or with S.S. This is mainly due to non-uniform distribution of carbon in higher thickness plates while manufacturing in steel industries. In addition the nominal tensile strength of the plate is in the 70 thousand psi range which is relatively higher. The general rule is to pre-heat and do PWHT if thk. of Mild Carbon Steel plates is 25 mm. or more and do PWHT only if thk. is 20mm or more.

Fine grained steels like ASTM 516 in thin and thick sections are normalised to improve their notch toughness so that they should meet their impact requirements at sub zero temperatures. Very heavy sections of fine grained steel are Quenched and Tempered, so that they acquire a micro structure whose toughness matches with that of thinner normalised sections.

Normalised grades can be welded as easily as mild steel with out any precautions. In case of Q & T steels, heat input control is necessary when welded and generally it should be below 3.0 KJ/mm (see heat input formula) and could be maintained by proper selection of procedures and consumables.

Since both materials have different melting points, thermal conductivity, coefficient of expansion etc.,your problem of PWHT could be solved to by buttering the surface of CS where weld to be done using 309 type consumables. The final weld then is made between buttered SS face to SS tube and l You an get proper heat balance

Metallurgically, the weld metal will have a single phase and mechanical properties are determined partially by it. The weld will have a max. of one layer or so for the thin SS tube and will not alter the hardness in the CS plate.

Further, if post heating is done, it will be problematic as heat is applied to one metal (CS) and it will be harmful for the other (SS) metal and may make it sensitive to inter granular corrosion. Other Wise you can use a stabilized SS filler metal.

Though you have not indicatead the application area of the joint, you can avoid PWHT for your joint .

Sridhar.

Dear sir,

Can anyone suggest me how to prepare Inspection and test plan and quality control plan for piping?

Thank you,

Ilangkumaran

Step one:

Interview welding metallurgist/engineer.

Step two:

Hire/contract said metallurgist/engineer.

Step three:

have said engineer/metallurgist produce required documentation.

Step four:

pay the man.

My point being, if you don't know how to do this, you are not qualified to be doing this and any information you would get from us would be suspect. You don't have enough knowledge to know if we are steering you right or not. Hire someone who knows what they are doing, the life you save might be your own.