API 5CT-Gr. K55 structural properties.

Question

API 5CT-Gr. K55 structural properties.

humanengr (Structural)

(OP)

21 Feb 18 21:27

Just checking if anyone has seen API 5CT- Grade K55 used for structural purposes.
(Steel piles in this case).
The chemical composition table (Table C.4 in API 5CT) does not list any limits (max. or min.) for any elements other than Phosphorous (P) and Sulfur(S).
Without a max./min. on critical elements including Carbon, I don’t see how Gr. K55 can be used for
structural purposes.
I've also seen test results reporting E=23,000+/- or about 20% less than the 29,000 ksi value used for steel design.
Any feedback would be appreciated.
I’ll also post this in the Structural Forum

blacksmith37 (Materials) · Answer 1 · 2018-02-21 22:21:45

The only intended use is for well casing with threaded couplings , yield strength 55,000 psi.

MarriolaV (Materials) · Answer 2 · 2018-02-21 22:32:34

I saw people make bridges for light traffic on rough terrain and local roads, but only to avoid discarding used pipe.

New only for casing.

KevinNZ (Mechanical) · Answer 3 · 2018-02-21 22:33:03

I would think this depends on the structural code you are designing to and how this treats non listed materials and testing/certification of these.

Note casing can be brittle at ambient temperatures.

LittleInch (Petroleum) · Answer 4 · 2018-02-22 12:33:37

API 5CT is, as said above Casing pipe of which K55 is a fairly basic grade and is designed as a screwed connection and not tested at low temperature or to any great extent.

I don't think it can be used for any other purpose without more testing and addition of elements to the specification.

Does someone just have a pile of this hanging around?

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API 5CT-Gr. K55 structural properties.