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Casing and Liner Colour Codes

Colour Codes for New Casing/Liner

All new casing shall be colour coded for yield as per API specifications 5CT.

API Casing/Liner Grade Identification Colour Codes

API Grade

Markings On Pipe Body

Markings on Coupling

P-110

One white band

White coupling

L-80


N-80

One red band and one brown band

One red band

Red coupling with brown band or longitudinal stripe

Red coupling

C-75

One blue band

Blue coupling

K-55

J-55

Two green bands

One green band
No colour marking or block at manufacturer’s option

Green coupling

Green coupling
No colour marking or at manufacturer’s option

Note: Marking should be applied 2 ft from each end

Colour Codes for Recovered Casing/Liner

Casing recovered from rigs whether new casing or old casing shall be cleaned and inspected prior to re-stocking. An in-house colour code should be applied to the casing body in addition to the API yield grade code on the coupling to identify the inspected casing. Currently, hardly any casing is recovered because of the cost hence coding/re-stocking is not formalised.

Casing/Liner Connections

API, BTC threads are used in most low exposure applications as these are highly dependable threaded connections. Premium (VAM etc.,) connections are used in situations such as oil and gas well production strings where gas tight, metal-to-metal seals are required.