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API 6A Wellhead Temperature Class and Material Class Reference

API 6A defines how wellhead and Christmas tree equipment is classified so a buyer and a manufacturer mean the same thing by 'a 5,000 psi, DD, T, PSL 3 spool'. This table puts the temperature classes, material classes, pressure ratings and product specification levels on one page you can search and export.

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Group	Code	Meaning	Detail (F / C or description)
Temperature class	K	Operating range	-75 F to 180 F (-60 C to 82 C)
Temperature class	L	Operating range	-50 F to 180 F (-46 C to 82 C)
Temperature class	P	Operating range	-20 F to 180 F (-29 C to 82 C)
Temperature class	R	Room temperature	Used for room temperature rating, typically for testing
Temperature class	S	Operating range	0 F to 150 F (-18 C to 66 C)
Temperature class	T	Operating range	0 F to 180 F (-18 C to 82 C)
Temperature class	U	Operating range	0 F to 250 F (-18 C to 121 C)
Temperature class	V	Operating range	35 F to 250 F (2 C to 121 C)
Temperature class	X	Operating range	0 F to 350 F (-18 C to 177 C)
Temperature class	Y	Operating range	0 F to 650 F (-18 C to 343 C)
Material class	AA	General service	Carbon or low alloy steel body, bonnet and end connections
Material class	BB	General service	Carbon or low alloy steel body, with stainless steel trim
Material class	CC	General service	Stainless steel body, bonnet and end connections
Material class	DD	Sour service	Carbon or low alloy steel body, meets NACE MR0175 / ISO 15156 requirements
Material class	EE	Sour service	Carbon or low alloy steel body, with stainless steel trim, sour service
Material class	FF	Sour service	Stainless steel body, sour service
Material class	HH	Sour service	Corrosion resistant alloy body and trim, most severe service
Rated working pressure	2,000 psi	13.8 MPa	Lowest standard API 6A rating
Rated working pressure	3,000 psi	20.7 MPa	Standard API 6A rating
Rated working pressure	5,000 psi	34.5 MPa	Standard API 6A rating
Rated working pressure	10,000 psi	69.0 MPa	Standard API 6A rating
Rated working pressure	15,000 psi	103.5 MPa	Standard API 6A rating
Rated working pressure	20,000 psi	138.0 MPa	Highest standard API 6A rating
Product specification level	PSL 1	Baseline	Basic quality, traceability and testing requirements
Product specification level	PSL 2	Intermediate	Adds requirements to PSL 1 for materials, testing and records
Product specification level	PSL 3	Higher	Adds requirements to PSL 2, including tighter NDE and traceability
Product specification level	PSL 3G	Higher with gas test	PSL 3 plus gas testing of the assembled equipment
Product specification level	PSL 4	Highest	Most stringent requirements, typically for critical high pressure service

Temperature ranges and class letters are for orientation. Always confirm the current edition of API Specification 6A and the customer purchase specification before quoting or marking equipment.

Structure API 6A codes in your ERP

Optional review of how pressure, material class, temperature class and PSL are stored on your item master.

Optional. The tool and every export work without this. No spam.

How to use the table

Type a letter, a pressure or a keyword such as 'sour' into the search box to filter rows. A typical order line combines four codes: rated working pressure, material class, temperature class and PSL. Use the table to decode a customer enquiry, check that an item master description is complete, or build the marking string for a nameplate. Export to Excel to paste the codes into a quoting template or a validation list.

What each group means

The temperature class sets the minimum and maximum temperatures the equipment is rated for, and drives impact testing and material selection. The material class describes the body material and whether it is suitable for sour (H2S) service. The pressure rating is the rated working pressure, not the test pressure. The PSL sets the level of quality control, traceability and testing, with PSL 1 as the baseline and higher levels adding requirements.

Temperature class letters are not alphabetical in severity, read the range.
Material classes DD to HH are the sour service classes.
PSL 3G is PSL 3 with gas testing, not a separate material level.

Worked example

A customer asks for 10K, EE, U, PSL 3. That is a 10,000 psi rated working pressure, sour service carbon or low alloy body with stainless trim, a 0 F to 250 F operating range, and PSL 3 quality requirements. Each of those four codes should exist as a field or a structured attribute on the item, the routing and the quality plan, so the right NDE, hardness testing and records are triggered automatically.

Common mistakes

Mixing up working pressure and hydrostatic test pressure is the most frequent error. Another is quoting a lower PSL than the customer specification requires, which then fails document review at shipment. Treating a sour service class as a purchasing note rather than a controlled attribute also causes escapes. Keep the class codes as structured data in the ERP, not free text in the description.

Frequently Asked Questions

What does API 6A cover?

API Specification 6A covers wellhead and Christmas tree equipment, including spools, bodies, bonnets, end connections and related items. It defines design, materials, testing, marking and documentation requirements for that equipment.

Is PSL 3G a higher level than PSL 3?

PSL 3G is PSL 3 with the addition of gas testing on the assembled equipment. It is not a stronger material requirement, it adds a specific test. Check the customer specification to see whether gas testing is required.

Which material classes are sour service?

In the API 6A scheme, classes DD, EE, FF and HH are the sour service classes, and AA, BB and CC are general service. Sour service materials must also satisfy NACE MR0175 / ISO 15156 requirements.

Is this table a replacement for the standard?

No. It is a quick lookup. Edition changes, footnotes and special cases live in the standard itself, so always verify against the current API 6A edition and your customer specification before committing to a design or a marking.

If your ERP stores these codes as free text, we can help structure them so quality plans, routings and certificates pick them up automatically.

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