the use of LTCS instead of CS material above - 29°C to avoid impact test of CS

[boudjema]

I need help about one subject related to piping material selection.
For reasons of delivery time of the piping and accessories contractor asks to use LTCS instead of CS with impact test for the pipes greater or equal to 12.7 mm thickness, is it possible to use LTCS material instead of CS material within a T° range of -29°C to 340°C, instead of using CS material to avoid Impact test.
If for some reasons we want to keep the same material of valves (CS) those valves will be installed in LTCS lines but within the T° range stated above.
is there any corrosion problem if joining LTCS flanges with CS valves, what is the suitable bolting material that can be used.
Regards

 

[bobjustbob]

If you put your low temp valves and standard CS valves on a spectrometer I doubt you would be able to spot the difference. When we make cast carbon steel valves, the chemistry range for A216 WCC and A352 LCC are very similar. Internal chemistry ranges at our facility allowed us to pour WCC, WCB, LCC and LCB all out of the same heat. The WCC/WCB are heat treated differently than the LCC/LCB but chemistry and tensile properties are similar to the point that if you don't know what you are looking for it would be difficult to find it.

I have never dealt with the forged valve materials but I would expect it to be a similar situation.

Bob

 

[weldstan]

In your stated temperature range, the LTCS is quite suitable with essentially no corrosion problems mating to CS calves.

 

[Dhurjati Sen]

Dear boudjema,

Few questions you need to have answers...

1. Why would the contractor provide LTCS in place of CS? Is he fudging the MTCs? Where are these pipes manufactured....China maybe?

2. What is the service, by the way?

If you don't want to dig deep, then weldstan has the answer.

Regards.

DHURJATI SEN

https://www.nace.org/people/dhurjatisen

 

[SJones]

Just because it is denoted 'LTCS' doesn't mean that it will melt above 0 deg C. Check B31.3 Table A-1 and compare A106 Gr B with A 333 Gr 6. The bolting material will be A193 B7 or similar, probably as originally selected. The only issue with the substitution will be leaving a traceable record as to why low temperature material is sitting in a higher temperature system. Normally, this would be a note on the materials selection diagram or in the materials selection report.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

I'm acronym-challenged - what is LTCS?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[bobjustbob]

Low temperature carbon steel.

Bob

 

[Chumpes]

Is there an official definition of "LTCS" (low temperature carbon steel) ? curve D of UCS-66 ?
I've also already seen ITCS for Impact Tested Carbon Steel, which does not presume the actual reference temperature for impact testing.

 

My doctor long ago diagnosed me with AOS*
.
* Acronym Overload Syndrome

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[bobjustbob]

I don't know about pipe but for cast valves we have two ASTM standards that cover the majority of the carbon steel valves.

ASTM A216 Standard Specification for Steel Castings, Carbon, Suitable for Fusion Welding, for High-Temperature Service

and

ASTM A352 Standard Specification for Steel Castings, Ferritic and Martensitic, for Pressure-Containing Parts, Suitable for Low-Temperature Service

The ASME SA standards are generally the same but the revisions lag behind the ASTM.

Bob