stainless to carbon fillet welds

[pipe15]

is it acceptable to weld a stainless steel thermowell into a carbon steel sockolet. This will result in a fillet weld between two dissimilar metals with coefficients of thermal expansion which differ by ~ 50%.

thanks
Mark

 

[BigInch]

Don't think I would do it. Thermal stresses can be excessive with a large temperature difference? Take the max temperature change, calculate the differential strain and the resulting expansion stress. Does the weld yield? If that's acceptable, then you still have to worry about dissimilar metal. Don't like worrying. Threaded joints in H2S service worry me more than enough.