The short answer
Ball, gate, check and plug valves are the main pipeline valve types covered by API 6D. They differ in how they open, seal and pass flow, so the right choice depends on the service, pressure class, piggability and operation the engineer specifies. Use this page to prepare questions, not to choose a valve.
The questions each type raises
| Type | How it works | Questions to settle |
|---|---|---|
| Ball | A bored ball turns a quarter-turn to open or close | Full or reduced bore? Floating or trunnion-mounted? Soft or metal seats? Fire-safe needed? |
| Gate | A gate moves across the flow path | Which gate design? Is a full, unobstructed bore needed? Operating torque and actuation? |
| Check | Opens with forward flow and closes against reverse flow | Which check design? Minimum flow for stable opening? Piggable? |
| Plug | A plug turns a quarter-turn; some designs are lubricated | Lubricated or non-lubricated? Sealing and maintenance needs? |
This is a procurement orientation only. Valve selection for oil and gas service is an engineering decision made against the approved datasheet.
Next, prepare the RFQ specification checklist or return to the pipeline valve procurement guide.
Sources
External facts on this page come from these sources, each read on 15 October 2026. Regulations change; requirements for your vehicle are confirmed during quotation and clearance. This guide is not legal or financial advice.
- API SPEC 6D: Specification for Valves, 25th edition (Nov 2021; Addendum 3, Mar 2025) — American Petroleum Institute webstore
- API STD 607: Fire Test for Quarter-turn Valves and Valves Equipped with Non-Metallic Seats, 8th edition (Oct 2022) — American Petroleum Institute webstore