Weld Overlay Limit

[jgibbs22]

​

Does the ASME Code (Division 1 or 2) limit the amount of weld overlay that could be used on a component to increase the overall thickness to handle a higher pressure? Example, if I had a 12" Diameter Carbon steel shell that is 1" thick, is there a limit to how much weld overlay could be put on it for increasing the thickness? Not really a practical thing necessarily to do of course, but more of a general question of what the Code would allow.

 

[EdStainless]

I believe that under most conditions you are not allowed to take credit for the overlay when considering the pressure rating.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[Don56]

EdStainless is correct. See Sect. VIII D1 UW-42. Overlay can be used to restore thickness not increase it.

 

[jgibbs22]

Thank you!! Is that the same for Division 2 as well??

 

[jgibbs22]

Also, that section refers to weld buildup, but not weld overlay. Are they considered one and the same for my question?

 

[jte]

One source for defining "buildup" vs. "overlay" is ASME PCC-2 Article 2.11 part 1.5. Simply put: "overlay" is different nominal chemistry, "buildup" is same nominal chemistry.

I'm not aware of explicit limits to weld buildup in VIII-1, certainly weld buildup is mentioned in UW. For example, UW-16(c)(1) explicitly mentions the use of weld buildup for opening reinforcement. While UW-42 has limits, I don't see that section as limiting the use of weld buildup outside the scope of this particular paragraph.

I haven't looked at Div. 2 in this regard.

 

[SnTMan]

Sec VIII, Div 1, Part UCL, UCL-23(c) does appear to allow weld overlay to be used as pressure retaining thickness. I personally have never seen it done, though. Usually treated as CA.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[JohnGP]

ASME VIII Div 1 has specific requirements for design and materials for weld overlay construction - see Part UCL -

REQUIREMENTS FOR WELDED PRESSURE VESSELS CONSTRUCTED OF MATERIAL WITH CORROSION RESISTANT INTEGRAL CLADDING, WELD METAL OVERLAY CLADDING, OR WITH APPLIED LININGS

UCL-23(c) includes requirements for including weld metal overlay thickness in the design calculations, i.e. calculations can be based on thickness of base material plus S_c/S_b (maximum value of 1.0) times nominal thickness of cladding, where S_c and S_b are maximum allowable stress values for weld overlay and base material respectively.

ASME VIII Div 2 Para 3.3.6 has the same requirements, pointing to para 4.1.9 for the same formula for calculating with weld overlay thickness included.

It is non-integrally attached linings for which no credit on thickness can be taken.

 

[JohnGP]

Ah, Mike beat me to the punch......must learn to type faster!

 

[metengr]

I believe that under most conditions you are not allowed to take credit for the overlay when considering the pressure rating.

Incorrect. If the weld overlay is of equal to or greater strength than the base metal you most certainly can take credit for pressure retaining thickness assuming a strength ratio of 1 (overlay strength to BM strength). You can't take credit for stronger overlay material.

 

[EdStainless]

But are the rules different for clad?
I have worked with people that have taken credit for a clad layer (explosive bond).
There have been discussions about what would be involved in taking credit for higher strength.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[marty007]

EdStainless,

Cladding can also be used for thickness calculations, but it comes with some additional testing requirements, see section UCL-11(c).

Briefly, this paragraph lays out some additional testing that must be performed to ensure adequate shear strength between the cladding and base metal. This paragraph discusses tests such as "Bond Strength" test as described in SA-263, SA-264, and a "Shear Strength" test.

In our experience, many customer specs specifically prohibit the use of any cladding in code calculations. As such, I know of these rules, but have never actually applied them...

 

[metengr]

Weld overlays are routinely performed for repairs on new construction NCR and existing equipment to restore strength. The weld metal is considered in the strength calculation. You just can't take credit for anything stronger otherwise we would be replacing tons of weld repaired components. Period.

 

[r6155]

The (OP) is "weld overlay", not "clad plate". Please, speak about "weld overlay"

Regards
r6155

 

[racookpe1978]

So, instead of buying the right thickness of steel, you want to spend hundreds of hours and hundreds of thousands of dollars to try to create the right thickness by welding more metal to a PV? How far away from that PV must we remain to stay safe?

 

[SnTMan]

racookpe1978, bonded cladding / weld overlay is not exactly about saving money on material thickness. It is about getting a combination of properties that either material alone won't provide. Such as the hot strength of a 1 1/4 Cr backer with the corrosion resistance of stainless. Although the resultant will likely be thinner that either alone, so in a sense you are saving money on thickness, but at added labor.

Very common construction in S&T exchangers, I don't know about other classes of work. As I said earlier, the thickness of the clad / overlay is rarely accounted for as pressure retaining.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

My experience is Reactor Pressure Vessel (Nuclear) 320 mm + 5 mm weld overlay stainless steel.

Regards
r6155

 

[racookpe1978]

SnTMan, r6155: That application is correct - Applying a continuous layer of weld material to obtain specific corrosion resistance (for a PV) or a new layer of wear-resistant alloy for a cutting or grinding surface.

But the original poster was specifically asking about adding weld metal to increase the PV wall thickness to add additional metal for pressure vessel qualification at a higher pressure. And that particular purpose - even assuming you can add enough metal by weld overlays and NDE and more weld overlay and final grinding to get a verified thickness - is many times more expensive than the original metal purchase price.

 

[SnTMan]

racookpe1978, my apologies, I misunderstood your point. I'd agree, poor way to "uprate" a vessel, if that is what was intended.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

"Does the ASME Code (Division 1 or 2) limit the amount of weld overlay that could be used on a component to increase the overall thickness to handle a higher pressure"

My reply: NO

Regards
r6155