316 Stainless Steel Material Call Out

[Mikepare]

How should I call out 316L stainless steel and passivation on a drawing? Right now I have Material 316L Stainless Steel and the thickness, Finish: Passivate. Are there military or other specifications that would quarantee material and finish quality?

I have heard of 316 marine grade stainless steel. What is the difference in the marine grade material. How would the marine grade be called out? What would the cost impact be of marine grade material?

Thanks

 

[kenvlach]

Mikepare,
I think everyone who followed the earlier thread330-42379 “Use of 316 stainless steel in a marine environment?” would like to hear about the results of your shipboard testing.

For specifications, you have a number of options for surface finish; chiefly, smoothness, impurity free and (electo)chemical finish:
Grind any welds.
Belt & then wet-polish; obviously, the smoother the finish the better; an R_a of < 0.5 is desirable.
Polishing media to be SiC or alumina, free of metals (non-stainless steel), and lubricated with S-free light cutting oil. [you can specify a final polishing grit size, e.g., 320 or finer: 400, 600…]
Pickle per ASTM A380 (or electropolish per ASTM B912-02, if mission-critical).
Passivate per QQ-P-35C or ASTM A967.

Not familiar with ‘marine-grade’ 316, but Carpenter Technology offers a premium-melted version of 316L: 316L-SCQ®, “which offers improved internal cleanliness (lower inclusion content)…”

I will add one last point: Annealed SS has better corrosion resistance than cold-worked.

 

[ijzer]

The ASTM A 480 specifies all kind of finishes for plate and sheet using a finish number.(1 up to 9)

 

[Mikepare]

The amount of data received from the barge has been limited. We sent out four 12X12 316L samples in early February. One was just sheared from the sheet, One was cut and time saved, One was cut and passivated and one was cut timesaved and passivated. Unfortunatley the ship yard did not get the samples on a barge until about one week ago. So far no sign of corrosion on any parts. We have also shipped the first 16 completed units to the barge, they will be installed and operational the week of 3/16/03. I feel confident that the combination of 316L and passivation will give us a noticable improvement.