GOST 12821-80 PDF

Full title and description

GOST 12821-80 — "Фланцы стальные приварные встык на Ру от 0,1 до 20,0 МПа (от 1 до 200 кгс/см²). Конструкция и размеры" (English: Steel butt-welded (weld‑neck) flanges for PN from 0.1 to 20.0 MPa — design and dimensions). This is the 1980 USSR national standard that defines types, dimensions, sealing-face variants and basic technical requirements for welded‑neck flanges used on pipelines, fittings and equipment.

Abstract

This standard specifies the constructional drawings, tabulated dimensions, pressure (nominal pressure PN/Ru) and temperature ranges, marking and basic technical requirements for steel butt‑welded (weld‑neck) flanges intended for pipeline and equipment connections. It was issued in 1980 and subsequently reprinted with amendments; its provisions served as a national design reference until unified flange standards were adopted.

General information

• Status: Historically an active USSR GOST; later formally replaced/superseded by the unified flange standard GOST 33259‑2015 (but retained in many technical references and reprints).
• Publication date: Approved 20 May 1980; date of mandatory introduction listed as 01 January 1983 (reissues and amendments published later).
• Publisher: USSR State Committee for Standards (Gosstandart / Государственный комитет СССР по стандартам).
• ICS / categories: Pipelines and their components — flanges, couplings and connections (OKC/ICS class around 23.040.60).
• Edition / version: Original designation GOST 12821‑80 (1980); reprinted with amendments (noted reissue editions in 1996 and earlier amendment sheets).
• Number of pages: Published editions commonly available list the standard at about 27 pages (varies by publisher/format and language version).

Scope

Applies to steel butt‑welded (weld‑neck) flanges for pipelines, connecting parts, fittings, valves, machine and instrument attachment flanges and vessel/nozzle connections with nominal pressure (Ru / PN) from 0.1 to 20.0 MPa (1 to 200 kgf/cm²). The standard covers flange construction and overall dimensions, allowable temperature ranges for service (shown as approx. from −253 °C to +600 °C depending on material and execution), sealing face types and typical manufacturing/marking requirements.

Key topics and requirements

• Definition of flange types and outline/constructional drawings for weld‑neck (butt‑welded) flanges.
• Tabulated overall dimensions (DN, bolt‑circle, number and size of bolt holes, bore, thickness, hub dimensions) for PN classes up to 20 MPa.
• Sealing face variants and recommended surface types/finishes for different pressure ranges and gasket types.
• Material recommendations and temperature/pressure application limits (carbon, alloy and stainless steels commonly referenced).
• Marking, tolerances, mass (weight) data and basic inspection/acceptance notes.
• Normative references to related flange and fastener standards and provisions for special executions (corrosion‑resistant steels, high‑temperature variants, ring‑joint types, etc.).

Typical use and users

Used by flange and pressure‑part manufacturers, piping designers and engineers, procurement specialists, project engineers in oil & gas, petrochemical, power generation, shipbuilding and heavy industry where flanged welded connections are required. Also consulted by maintenance and inspection teams when replacing or verifying flange compatibility on existing systems originally built to Soviet/Russian GOST dimensions.

Related standards

Closely related to other historical GOST flange standards (for example GOST 12820‑80, GOST 12822‑80 and GOST 12815‑80) and later consolidated in the unified GOST 33259‑2015 ("Flanges for valves, fittings and pipelines up to PN 250 — design, dimensions and general technical requirements"). International equivalents/points of comparison include ISO 7005 and EN 1092 (weld‑neck / butt‑weld flange families); engineers should cross‑check GOST and ISO/EN dimensions when specifying replacements or interfacing components.

Keywords

GOST 12821‑80; weld‑neck flange; butt‑welded flange; steel flange; PN 0.1–20 MPa; Ru; flange dimensions; sealing face; ГОСТ; pipe flanges; weld neck; flange marking.

FAQ

Q: What is this standard?

A: GOST 12821‑80 is a Soviet national standard (1980) that defines the design and dimensions of steel butt‑welded (weld‑neck) flanges for nominal pressures from 0.1 to 20.0 MPa, including dimensional tables, sealing face variants and basic technical requirements.

Q: What does it cover?

A: It covers constructional drawings, detailed dimensional tables (DN, bolt circle, bore, number of holes, thicknesses, hub geometry), sealing face types, service pressure/temperature ranges, marking and basic acceptance notes for welded‑neck flanges used on pipelines, fittings, valves and equipment.

Q: Who typically uses it?

A: Flange manufacturers, piping and mechanical designers, procurement and QA/QC teams in oil & gas, chemical, power, shipbuilding and process industries, plus maintenance staff working with legacy Soviet/Russian‑spec systems.

Q: Is it current or superseded?

A: The original 1980 standard has been superseded/merged into the later unified GOST 33259‑2015 for most modern applications; however, GOST 12821‑80 remains widely referenced in legacy documentation, manufacturer data sheets and some reprinted editions. When specifying or replacing flanges today, check whether GOST 33259‑2015 (or project‑specific requirements) is required.

Q: Is it part of a series?

A: Yes — it forms part of the family of GOST flange standards (for example GOST 12820, 12821, 12822, 12815, etc.) that historically covered flat, weld‑neck and loose flanges; these were later consolidated in unified flange standards.

Q: What are the key keywords?

A: Weld‑neck flange, butt‑welded flange, steel flange, PN (Ru), flange dimensions, sealing face, GOST, flange marking, DN, bolt circle.