Instrumentation Tubing specification 316/316 L 1

[shabbirvora]

We come regularly across Instrumentation Tubing which is manufatured to ASTM 269 A 213 Average Wall, Seamless, Cold Rolled, Annealed.
This usually comes from some reputed manufacturers and
The question arises is
1. They mention it is as grades 316/316 L; why not only
316 L
2. The confirmity certificate describes NACE requirements on
hardness of Tube <= 80 Hrb, but still if looked
properly through certificate you
see 83 to 85 Hrb;and on the contrary the certificate
never states cleary the complianc to NACE but only states
the NACE requirements.
The certificate is used to support material specs and
Nace compatiability.
What are reasons still this things are presented by
vendor for acceptance and nobody has complained.
Thanks

 

[kenvlach]

I see no reason for complaint with regard to ASTM A269. Perhaps someone with details re the NACE spec. will also answer.

1. To simplify manufacturing and inventory, tubing is produced to satisfy both 316 & 316L requirements. The 0.08 % C is a maximum, so simpler to have it all meet the 0.04% C max. of the L grade. Same for 304/304L, especially in the smaller diameters.

2. 316 & 316L per A269 shall have a hardness not exceeding 100 HRB. Note that hardness testing is not required on tubing smaller than ¼ inch ID or wall thickness < 0.020 inch.

3. Since corrosion seems to be a concern, note that A269 has supplementary requirements which you may also require: S1. Stress-Relieved Annealed Tubes and S4. Intergranular Corrosion Test. Compliance with A269, S1 may perhaps give a lower hardness in compliance with NACE.

 

[mcguire]

Welcome back, Kenvlach! I've been away for a while (and still am out of the country)but I haven't seen you in a long tome on the site.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[kenvlach]

Thanks, Professor McGuire,
I had been really burned out.
Congratulations on your new SS book.
Ken

 

[shabbirvora]

Thanks Kenvlach for your valuable input.
You are correct annealed tubing have lower hardness.
Since we are supposed to use this tubing with compression fittings the tubing odd to be around 80 Hrb.
For correct assembly Compression fitting has to have higher hardness to bite the tubing and at the same time hardness has to be within the NACE limits.
Thanks once again.