Section VIII, 2011a Ed.: UCL-11 (e)

[newweldeng09]

"When any part of the cladding thickness is specified as an allowance for corrosion, such added thickness shall be removed before mill tension tests are made."

In our case, we are cladding a CS plate with a SS plate using a solid state welding process. Does the above statement in the spec. mean that the corrosion allowance needs to be removed for tension tests that are to be performed at the mill for the SS plate only or after the cladding process for the CS plate cladded with the SS plate?

 

[gr2vessels]

Normally, the mill tension tests are intended for the carbon steel substrate, ignoring the additional strength provided by the stainless steel cladding. In order to truly test the substrate, the cladding has to be physically removed before the test. The stainless steel plate may come with its own tests and certs, but this plate counts only as corrosion resistant material. Refer to the excerpt below, from ASME SA-264:
"8.1.1.1 The tensile properties shall be determined by a tension test of the composite plate for clad plates that meet all of the following conditions. However, if the cladding is for corrosion allowance only, the cladding may be removed prior to tensile testing. The tensile properties thus determined shall be not less than the minimum and not more than 5000 psi (35 MPa) over the maximum prescribed in the specification for the base steel used. All other tensile test requirements of the specification for the base steel shall be met."
However, if you include the stainless steel in the composite material, then the tensile test shall include the cladding. The exception in UCL-11(e) refers to the part thickness of the cladding material already deposited on the substrate, intended as consumable corrosion allowance (expected to be removed in service by the process). Eg. 6 mm stainless steel cladding, out of which 3.4 mm minimum thickness of pure SS chemical analysis + 1.6 mm contaminated composition + 1.0 mm corrosion allowance;- remove top 1 mm corrosion allowance before tensile test.
Cheers,
gr2vessels