Q1: What if T-shoe is of CS for SS piping running on the Piping rack. What results are expected?
Q2: If a tank is subjected to CP & earthing simultaneously, how do two systems work separately without interfering each other despite they have somewhat opposite science?
Q3: What are the precautions to carry hydro testing of buried U/G pipe?
MIsc Questions
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Usman Amin
- Senior Member
- Posts: 30
- Joined: 02 Apr 2010, 07:06
- Area of interest: Metallurgy Engineering
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ashfaqanwer
- Site Admin
- Posts: 443
- Joined: 16 Mar 2010, 03:36
Re: MIsc Questions
Usman,
1. CS supports for SS piping are not recommended to install. The main reason is SS contamination which would occur at the contact point. This would result in elimination of oxide layer which would eventually corrode forming pitting points. It is always a good practice to use some insulating material in between carbon steel support and SS piping considering service conditions. I can further look into your situation if you can please just share the conditions of SS piping like movement, service temperature etc.
2. I would suggest if you may please raise this query separately in Inspection & Reliability Engineers forum.
3. For hydrostatic testing of underground piping in addition to all precautions you take for A/G piping following shall be considered:
- If the weld joints are exposed, holding time must be 2 hours instead of min. 1 hour for A/G piping.
- In case line has been backfilled due to safety concerns or other, and visual check of all the weld joints is not practical, test time shall be at least 24 hours with automatic pressure-temperature recorder installed.
Hope this would help.
1. CS supports for SS piping are not recommended to install. The main reason is SS contamination which would occur at the contact point. This would result in elimination of oxide layer which would eventually corrode forming pitting points. It is always a good practice to use some insulating material in between carbon steel support and SS piping considering service conditions. I can further look into your situation if you can please just share the conditions of SS piping like movement, service temperature etc.
2. I would suggest if you may please raise this query separately in Inspection & Reliability Engineers forum.
3. For hydrostatic testing of underground piping in addition to all precautions you take for A/G piping following shall be considered:
- If the weld joints are exposed, holding time must be 2 hours instead of min. 1 hour for A/G piping.
- In case line has been backfilled due to safety concerns or other, and visual check of all the weld joints is not practical, test time shall be at least 24 hours with automatic pressure-temperature recorder installed.
Hope this would help.
Ashfaq Anwer
-PetroStreet.com
-PetroStreet.com
Re: MIsc Questions
Regarding CS supports on SS ping, it depends a lot on the environment; water ingress in the area, moisture content / humidity, open atmosphere would cause galvanic corrosion and would lead to corrosion of stainless steel pipe.
In addition to this, if the pipe has to deal with high temperature fluid, co-efficient of thermal expansion for carbon steel and stainless steel is different. This has to be considered if the CS support is directly welded to SS pipe.
In addition to this, if the pipe has to deal with high temperature fluid, co-efficient of thermal expansion for carbon steel and stainless steel is different. This has to be considered if the CS support is directly welded to SS pipe.