API Spec 12D-2025 PDF

Full title and description

API SPEC 12D: Specification for Field‑Welded Tanks for Storage of Production Liquids — Thirteenth Edition (2025). This technical specification establishes materials, design, fabrication, welding, inspection and testing requirements for vertical, cylindrical, aboveground, closed‑top, field‑welded steel storage tanks used in oil production and similar services at near‑atmospheric internal pressures.

Abstract

This specification provides minimum requirements for the material selection, structural design, fabrication methods, welding procedures, non‑destructive examination, testing and pressure/venting considerations for field‑erected welded steel tanks used to store production liquids (crude oil and related liquids). It is intended to ensure safe, economical storage tanks suitable for the production segment of the petroleum industry and to serve as a common ordering/fabrication reference for manufacturers and purchasers.

General information

• Status: Current / In force.
• Publication date: May 2025 (Thirteenth Edition; published May 2025).
• Publisher: American Petroleum Institute (API).
• ICS / categories: 75.180 / 75.200 — Equipment and handling for petroleum and related products (petroleum storage and handling equipment).
• Edition / version: 13 (Thirteenth Edition, 2025).
• Number of pages: Listed as approximately 31 pages by multiple distributors (some listings show 31–34 pages depending on distributor formatting).

Scope

Applies to vertical, cylindrical, aboveground, closed‑top, welded steel storage tanks sized and rated for internal pressures approximately atmospheric, intended for storage of production liquids (including crude petroleum and similar liquids). The standard covers requirements for materials, design (including maximum allowable pressures and dimensions), fabrication, field welding, non‑destructive examination, testing, and marking, and is intended for tank manufacturers, field erectors and purchasers in the oil production industry.

Key topics and requirements

• Material specifications for shell, bottom and roof plates and permitted materials.
• Design rules for vertical cylindrical shells, roof types and roof supports; allowable internal pressures (near atmospheric) and capacity ranges.
• Fabrication and field‑welding procedures, welder qualifications, welding inspection and acceptance criteria.
• Non‑destructive examination (NDE) requirements and sampling/acceptance levels for welds and joints.
• Hydrostatic and pneumatic testing procedures and pre‑commissioning checks.
• Marking, documentation and purchaser/manufacturer responsibilities for ordering and acceptance.
• Notes on API Monogram program timing and related program effective dates for equipment branding.

Typical use and users

Used by oilfield equipment manufacturers, tank fabricators, site erectors, inspection and testing contractors, pipeline and production operators, procurement teams specifying field‑erected storage tanks, and regulatory or compliance personnel who reference industry practice for design and testing of production storage tanks.

Related standards

Closely related API and industry documents include other API 12 series specifications (shop‑welded tank specifications and related documents), API 12R1 (installation, operation and maintenance guidance for production tanks), and complementary API standards covering tank inspection, pressure‑relief devices and materials. Users commonly consult these related API documents and national/regional codes when designing, constructing and inspecting storage tanks.

Keywords

field‑welded tanks, storage tanks, production liquids, API SPEC 12D, aboveground storage tanks (AST), tank fabrication, tank welding, NDE, hydrostatic testing, petroleum storage

FAQ

Q: What is this standard?

A: API SPEC 12D is the American Petroleum Institute specification that sets minimum requirements for the materials, design, fabrication, welding, testing and inspection of vertical, aboveground, field‑welded steel storage tanks used in production service.

Q: What does it cover?

A: It covers selection of materials, structural design rules for shells and roofs, fabrication and field welding practices, welder qualifications, NDE and testing procedures (including hydrostatic tests), documentation and marking requirements for field‑erected tanks intended for near‑atmospheric service.

Q: Who typically uses it?

A: Tank manufacturers, field erection contractors, oil and gas production operators, procurement/specification engineers, inspectors and testing organizations use this specification as a primary engineering and purchasing reference.

Q: Is it current or superseded?

A: The 2025 (Thirteenth) edition is listed as the current edition (published May 2025). Users should confirm status with API or authorized distributors for corrections or errata and verify any regional regulatory adoption dates.

Q: Is it part of a series?

A: Yes — it is part of the API 12 series of specifications and guidance documents addressing shop‑ and field‑fabricated storage tanks and related installation/inspection practices; other API 12xx documents cover shop‑welded tanks, installation and maintenance guidance.

Q: What are the key keywords?

A: field‑welded tanks; aboveground storage tank (AST); production liquids; tank fabrication; welding and NDE; hydrostatic testing; API 12D; petroleum storage.