316 or 316L Dual Certification

The difference between the SS316 and SS316L is the carbon content. The carbon content is restricted to a maximum of 0.03% for SS316L, while SS316 allows maximum carbon is 0.08% and in some grades it can be as high as 0.15% max. This lower level of carbon is usually used where welding is performed. So, if you don't need welding, SS316 should be ok if there is no other reason (such as the spec.) to restrict its use there.

- MS

Dear maraamaram,

Regarding your 316 and 316L dual certfication issue, unltimately it depends on your application, i.e is your vessel a pressure vessel, or a straight-forward fabricated structure. Since there is no electrolysis issue will either 316 and 316L Stainless Steel in a H2S evironment, then it would seem unlikely you need to worry about whether you use pure 316 stainless steel bolts and fixings or 316L. Nonetheless, you should consult your client in regard to their welding specifications in case they specify 316L, otherwise 316 will comply in all classes of structure which have welding issues.

If I can be further assistance, do not hesitate to communicate by return.

Yours respectfully,

A.R.J

"dual certified" means you get the worst of both worlds. Whoever came up with that idea needs to be strung up by his gonads and allow passers by three whacks with a stick for a buck. He deserves all that and more.

316L has very low carbon levels (>.03% is typical) to prevent sensitization in welds. 316 has higher carbon content for strength. "dual certified" means you have more carbon than you really want for a weld, and not enough to give you decent strength.

For H2S service, cold worked fasteners are NOT ALLOWED per NACE MR0175. the fasteners have to be in the annealed condition with no cold work in the threads or the head. ASTM A193 B8MA or similar.