SS316 vs SS316L 1

[Kaleem1013]

I understand that the difference between SS316 and SS316L is the amount of carbon content in the material. It is in less percentage in 316L than in 316. And CF3M and SS316L are the same except the latter is forged and the former is cast body.

This difference, is it only valid when there is welding involved or does it also makes a difference in the kind of medium in the pipelines.

In one of the projects we are working on, we have proposed to use SS316L valves for all socket weld types (because of welding involved between valve and pipe) and to use SS316 valves for RF valves (no welding required, valves will be bolted to mating flanges).


Is this reason good enough?

 

[cloa]

http://www.dezurik.com/getdoc/2fc8e037-7ef1-4625-83cf-d70bbb9b5c54/S10_60_6-pdf.aspx

Some difference in strength allowable between L and standard forms but there is dual rated materials.

 

[katmar]

It has always been my understanding that the L (or Ti) grade was primarily for weldability.

Katmar Software - AioFlo Pipe Hydraulics

http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"

 

[cloa]

Its not really for weldability which is simple how easily it is to weld (join) using a given process but rather propensity to sensitive the stainless steel so reducing its corrosion resistance.

 

[Kaleem1013]

Thanks Cloa and Katmar.

Cloa - can you please elaborate "propensity to sensitive stainless steel".
The medium in the pipelines is Jet Fuel. My line size is 2", And the pipes used are 2" SS316L , Sch 40 with mating Flanges 2" 150# RF F316L, B16.5

The chemical compatibility of Stainless Steel - 316 with Jet Fuel comes as "A-Excellent" as per

http://www.coleparmer.com/Chemical-Resistance

Appreciate your help!

 

[gerhardl]

Any addition with 'Ti' for titanium content in 316 material is also for improved mechanical forming by turning etc.

 

[katmar]

cloa is correct - I didn't phrase my reply well at all. When welding 316 the carbon tends to migrate and affect the crystal structure in the heat affected zone. The carbon binds with the chrome and prevents it from doing its duty in actually forming a corrosion resistant oxide layer.

Katmar Software - AioFlo Pipe Hydraulics

http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"

 

[bingbingwang]

SS316 and SS316L are different on hardness, therefore, a little different on process applications. example, H2S service needs SS316L not SS316. depends on where you are gonna use them.

Get help and return with helps!!.