stainless steel 316/316L vs 316L - Swagelok Leipzig | Berlin

A frequently asked question to our employees is the following:

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Contact us to discuss your requirements of 316 and 316L Valve Balls. Our experienced sales team can help you identify the options that best suit your needs.

Can you offer your fittings in 316L stainless steel?

The answer is in most cases: Yes, we could also offer you the 316L stainless steel product. The manufacture of these special products requires appropriate planning and procurement in addition to the actual series production. This generally results in much longer delivery times than when using our standard 316/316L stainless steel.

Due to the production of small batch sizes, the prices for the specials are also usually higher than for the standards. Also minimum order quantities and proportionate set-up costs for the production can arise, which makes the use of these screw connections unattractive for you.

For these reasons, we always recommend that you orient yourself towards stainless steel 316/316L.

Not only these facts speak for the use of stainless steel 316/316L but also technical reasons. We will take a closer look at these in the following.

If you are looking for more details, kindly visit 304 and 304L Valve Balls.

Chemical composition of stainless steel 316 and 316/316L

Ni Cr C 316L ASTM
A479/A182 10 bis 14% 16 bis 18% 0,030 % 316/316L ASTM
A479/A182 10 bis 14% 16 bis 18% 316 = 0,08 %
316L = 0,030% 316/316L Swagelok Min. 12% Min. 17% 0,040% Austenitic structure more stable at 12% Ni. This ensures better deformable, embrittlement-resistant alloys. Higher corrosion resistance as required at the lower limit 16% according to ASTM

What can be concluded from the data in the table?

• 316/316L stainless steel is also called dual certified stainless steel because it complies with 316 and 316L stainless steel standards. We can also prove this fact with the 3.1 certificate according to EN .
• The 316L stainless steel has a slightly lower carbon content than the 316L stainless steel. The 316/316L stainless steel we use is close to the carbon content of the 316L stainless steel.
• The stainless steel used by Swagelok provides the better quality required by the ASTM lower limit due to the higher alloy content of chromium and nickel.

One thing to keep in mind is that material specifications often overlap one another. So, a material that falls into the overlap can be certified for both. For a simplistic example, let's say one material specification requires a particular constituent to be 2%-5% of the total mass and another material specifications requires that same constituent to be 3%-7% of the total mass. All other things being equal, if your material has 4% of that constituent, if qualifies for both; 2.5% or 6%, it doesn't.

I have run across this before with bronze alloys (of which there seem to be infinite number), steel for water well casings, cement, and probably a few others I have forgotten about.
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[li]With bronze, I see this most often in manufacturer's "recommended specifications" for valves and pumps for service in water distribution systems. One manufacturer will call out one bronze alloy for some part, while their competitors will call out other bronze alloys. These alloys are usually from the same alloy family and often have overlapping specifications. Manufacturers will call out a particular bronze alloy in hopes you will use their specification for the project and thus limit the selection to their product. However, the likely overlaps usually mean at least some of their competitors will also qualify. The master specifications I use for public works projects have a broader envelope and rarely allow such proprietary designs.[/li]
[li]With steel for well casings, I was contending with a state regulator who said the well casing material I was proposing for a state-funded project (ASTM A139, Grade B) did not meet the state's water well regulations, even though it is one of the most popular steels used for well casings in this state. He was misinterpreting the regulations, of course, which he finally figured out after I wrote what amounted to a technical/legal brief proving my point. In fact, the proposed well casing material far exceeded the state's minimum requirements.[/li]
[li]With concrete, it all started for me when a subcontractor on a large project mistakenly used Type II cement (the most commonly used cement type around here) for about one hundred sewer manhole bases when our specs called out Type V cement, which is the most sulfate-resistant of the five cement types used in the USA. The government inspector had missed it and it was the prime contractor's site engineer who brought it to my attention. Rather than rip out all the manhole bases, he was suggesting a PVC liner to rectify the problem. Fortuitously, a few weeks earlier, our company's chief structural engineer had mentioned to me in an offhanded comment that some Type II cements also qualify as Type V. I called him to discuss this situation and he said that the mill the contractor was getting his cements from produced a Type II that qualified as Type V, but they had never certified it as such. He suggested I compare the two submittals I had received for Type II and Type V with ASTM C150 and see if this particular Type II also met the Type V requirements. The analysis was not too difficult, and sure enough this Type II also qualified as Type V. I contacted the site engineer and told him the cement was going to be OK and no PVC liner would be required, but I wanted a letter from the mill confirming that their Type II also qualified as Type V.[/li]
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