API Specification 5CT; API Specification 5B

Casing and Tubing Couplings

Order OCTG couplings by casing or tubing service, nominal pipe size, matched grades, exact thread connection and coupling dimensions. Provide clearance requirements, thread inspection, protection, quantities and destination. Confirm compatibility with the ordered pipe and connection before purchase.

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PRODUCT SPECIFICATIONS

KEY SPECIFICATIONS

Standard: API Specification 5CT; API Specification 5B
Nominal size: Nominal size matched to the parent pipe or assembly; confirm on quotation/PO.
Connection: Exact thread or connection designation and governing standard; confirm compatibility on PO.
Product: Casing and Tubing Couplings

Technical classification

Material / substrate: Carbon Steel
Form: Fitting
Application: Oil & Gas

Product specifications

Send grade, standard, dimensions, and delivery requirements for a matched product quotation.

Product specifications
Property	Value
Product identity
Product	Casing and Tubing Couplings
Material	Carbon Steel
Product form	Fitting
Standards and classification
Standard	API Specification 5CT; API Specification 5B
Dimensions
Nominal size	Nominal size matched to the parent pipe or assembly; confirm on quotation/PO.
Process and connections
Connection	Exact thread or connection designation and governing standard; confirm compatibility on PO.

Overview

A casing or tubing coupling is a threaded OCTG connection component matched to the pipe it joins. It is not specified by straight-pipe outside diameter and wall thickness alone, and it does not use an ASME flange pressure class. The RFQ should identify casing or tubing service, API Specification 5CT edition, nominal pipe size, matched grade, coupling type, and thread connection. API tubing references include EUE and NUE, while casing references include STC, LTC, and BTC where applicable. Proprietary or premium connections need the exact licensed designation, drawing, and inspection criteria. Buyers should state full-length or special-clearance requirements, dimensions, thread inspection, surface treatment, marking, thread protection, quantity, and service conditions. Compatibility with the ordered pipe and connection must be confirmed before release.

Product scope

Match the coupling to the ordered pipe and exact connection
Specify coupling dimensions and clearance requirements
Agree thread inspection, marking and protection

Applications

Couplings for a specified casing-string connection
Couplings for an approved tubing-string or replacement connection

Surface options

Surface treatment and storage protection specified by the order
Thread compound and protectors matched to the agreed connection

Processing & form

Coupling dimensions and clearance to the accepted specification
Thread gauging and inspection to the agreed connection standard and criteria

Packing, inspection & delivery documents

Include packing, material certificate and inspection requirements so costs and delivery arrangements can be reviewed together.

Packing & delivery

Export packing options

State thread protectors, storage protection, package quantities, maximum bundle or crate weight and lifting limits. Include the destination port and required delivery date. Confirm packing and delivery terms before order acceptance.

Quality assurance

Quality documents

Specify material identification, dimensional checks, applicable thread inspection, acceptance criteria and the required inspection certificate. Agree traceability, witness points and document availability in the quotation and purchase order.

FAQ

What data is needed to match a coupling to pipe?

Provide casing or tubing service, nominal pipe size, pipe and coupling grades, exact connection, coupling dimensions and clearance. Include the drawing when applicable. Check the proposed coupling against the complete pipe and connection specification before purchase.

Do matching size and paint colour prove connection compatibility?

No. Size and paint colour do not identify the complete thread geometry, material acceptance or service qualification. Use the exact connection designation and inspection criteria. Proprietary connections also require the applicable owner approval and licensing arrangements.

Does an API 5CT grade alone confirm sour-service suitability?

Provide the well service specification, operating environment and any additional material qualification or testing requirements. A grade name or reference to API 5CT alone does not establish suitability for a particular well.

Which inspection documents should the order specify?

Identify the required inspection certificate, material and heat identification, dimensional results and applicable thread inspection records. Add product-specific tests, acceptance criteria and witness points. Confirm the scope and document availability before placing the order.

Request an OCTG quotation

Send the pipe or coupling specification, connection details, quantities, inspection requirements and destination port.

Request a Quote Check details on WhatsApp

RFQ form: itemized quote, MTC and packing requirements
WhatsApp: quick check of specifications, quantity and port