Air cooler tubes BWG

[0707]

For duplex tubes 2505, O.D 25mm, in a highly corrosive environment with hydrogen and 6.2% wet H2S.

Pressure in 153.1 Barg, Pressure out 14 Barg

Temperature in 139ºC, Temperature out 60ºC

Velocity in 8.8m/s velocity out 7m/s.

Are BWG 16 tubes acceptable for an air cooler?


lm

 

[TomEun]

Based on the 15 years design life, it may be ok unless the HC service contains NH4HS, amine, CN-, HF, heavy chloride, etc.

 

[metengr]

0707;
There are really two questions here requiring more information before you can make a material choice;

1). Did you run a minimum wall calculation using the formula for tubing in ASME Section VIII, Div 1 for the stated conditions?

2). What does a highly corrosive environment with hydrogen and 6.2% wet H2S mean? Is this highly corrosive because of only hydrogen and H[sub]2[/sub]S or are there other contaminants to consider?

 

[EdStainless]

Unless you need the wall for pressure rating (which I doubt) you would be better off with thinner walls. If the tubes fail it will be by pitting, and extra thickness will not buy you any life extension.

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Plymouth Tube

 

[API123]

All very good advise and additional information should be added. Also be cautious of mechanical failure. The material you selected is subject to cracking due to excessive vibration or other means of mechanical stresses. Also look into thermal stresses and the requirements for "strength" welds vs seal welds or flared connections to your header boxes.

 

[strider6]

two considerations:
internal corrosion
-if you're under the NACE /ISO 15156 then you need to be carefull. The partial pressure limit of H2S for superduplex is 0.2 Bara (see Part 3 of nace /iso).

external corrosion
-139°C can cause external corrosion problem (CSCC)for a duplex materials in a marine (high chloride) environments.
see norsok M001 material selection (110°C is the limit for SDuplex)

http://www.ivt.ntnu.no/ipm/und/fag/k_i/robmat/Forelesningsmatriell/13.10.2004 NORSOK M-001.pdf

S



Corrosion Prevention & Corrosion Control

 

[0707]

This air cooler will cool down the effluent from hydro cracking high pressure separator, which comes from first stage reactor.

As contaminants we will have: Hydrogen, water with H2S, ammonium bisulphide less than 12%wt, amonium chloride, and HCL.


lm

 

[API123]

I would investigate the use of Incoloy 825 or maybe Inconel 625, also you may experience increased corrosion over 30 fps, so you are getting close.

If you use a duplex material, you may want to look into API 938 - C and fabricate a mock-up for testing. I witnessed the after effects of an ARDS Unit 2205 air cooler failure so maybe my opinion is jaded.

 

[EdStainless]

Don't bother with 625 unless you need high temp strength.
Flow related issues in 2205 are very possible, it isn't immune to corrosion, just fairly good. You might consider a super duplex, and have CFD done for flow related issues in the deisgn.

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Plymouth Tube