"Butter" Welding

[Duwe6]

"Butter" means to apply a layer of weldmetal over the basemetal, like buttering toast. If a pipe is too short when dropped into place, it can be pulled out and one [or both] ends "buttered" with weldmetal to lengthen it.

Basemetal with 'problem' properties like P22 or old, brittle oil tank material can be improved with "Buttering".

The P22 can be buttered with 625 or 309 and then PWHT'd. Then 300-series stainless can be welded to it without engendering more PWHT, that would damage the 300 s/s. You won't be welding to the P22, you will be welding to the butter.

To be able to add a large nozzle, or replace a door-sheet on a tank that was built with material that has known brittle-fracture properties, you "Butter" all the cut edges of tank with E7018 or some other very ductile weld material.

 

[vpl]

Thanks Duwe6 -- though maybe you want to create a FAQ so it doesn't get lost?

Patricia Lougheed

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[berkshire]

was this a reply to something like;
Welding of inconel tubes with P22 headers


B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[metengr]

Duwe6
I review your posts with interest and typically you are spot on. However,....

Basemetal with 'problem' properties like P22 or old, brittle oil tank material can be improved with "Buttering".

The above quote is a completely inaccurate statement and provides misleading information to people. Buttering does not improve any material for service. Creep damaged material, temper embrittled material or hydrogen damaged material WILL NOT be improved by buttering. Buttering is simply a weld deposition method. I could use the same logic in your statement and argue making circumferential or long seam butt or even pad welds on service damaged material will improve them for service. Absolute nonsense and dangerous to assume.

 

[Duwe6]

I agree buttering old brittle tank material sounds counterintuitive. It is, however, a technique used by Exxon to extend the usefulness of bad tanks. If a doorsheet was just directly welded back into a tank without any special techniques, there is a fairly high chance of cracking due to the poor material. After buttering both the tank proper and the edges of the doorsheet, it can be put back in the tank safely.

You are correct that you still have a tank that gets brittle every cold morning, and that tank has no business in hydrocarbon service because of cold-weather brittle-fracture problems. We used our 'problem tank' for water clairification. Still going good 20 years after we opened up, and replaced a big doorsheet.