GOST 6357-81 PDF

Full title and description

GOST 6357-81 — "Основные нормы взаимозаменяемости. Резьба трубная цилиндрическая" (Pipe cylindrical thread: profile, basic dimensions and tolerances). The standard defines the profile, principal dimensions and tolerances for cylindrical (parallel) pipe threads used in cylindrical threaded connections and in combinations of internal cylindrical threads with external conical threads under GOST 6211-81.

Abstract

This standard specifies the geometry, nominal sizes, pitches and tolerance classes for cylindrical (parallel) pipe threads applied in piping and fittings. It sets interchangeability norms for manufacture and inspection of external and internal cylindrical threads and describes permitted mating with conical external threads per the relevant provisions. The cylindrical thread described is non‑sealing by design and normally requires sealants or gaskets when used in pressure-bearing joints.

General information

• Status: Active / действующий (standard in force; originally approved in 1981 and introduced into effect 01.01.1983).
• Publication date: Designation year 1981 (GOST 6357-81); brought into force 1 January 1983 (with later reissues/updates recorded in national catalogues).
• Publisher: Originally approved by Gosstandart of the USSR; maintained in the Russian national standards catalogue (Rosstandart).
• ICS / categories: 21.040.30 — special screw threads (including pipe threads).
• Edition / version: GOST 6357-81 (replaces GOST 6357-73); text has recorded reprints and amendments in national databases.
• Number of pages: 8 pages (typical national publication record).

Scope

Applies to cylindrical (parallel) pipe threads used for assembly of threaded cylindrical connections across pipe fittings, valves and equipment. The standard defines thread profile, nominal diameters and pitches (inch‑based nominal sizes are used historically), dimensional tolerances and acceptable mating conditions — including how internal cylindrical threads may pair with external conical threads produced to GOST 6211-81. It is intended for manufacturers, designers and quality/inspection services working with threaded pipe components.

Key topics and requirements

• Thread profile and geometry for cylindrical (parallel) pipe threads (basic form, flank angle, pitch and gauge definitions).
• Nominal sizes and pitches (traditional pipe nominal sizes, inch-based designation for threads used on pipes and fittings).
• Dimensional tolerances and interchangeability limits for external and internal cylindrical threads.
• Rules for mating internal cylindrical threads with external conical threads per GOST 6211-81 (limitations and checking criteria).
• Functional note: cylindrical threads are non‑sealing by themselves — sealing must be provided by gaskets, joint sealants or other accessories (contrast with tapered threads which can be self‑sealing).
• Manufacturing and inspection recommendations to ensure interchangeability of threaded pipe components across suppliers and assemblies.

Typical use and users

Widely used by pipe and fitting manufacturers, mechanical and piping designers, HVAC and plumbing engineers, maintenance workshops and suppliers of threaded pipe components. Typical applications include low- to moderate-pressure water, steam and gas piping, plumbing fixtures, instrument connections and other installations where a parallel (cylindrical) thread with an added sealant or gasket is acceptable.

Related standards

Relevant and associated documents include: GOST 6211-81 (pipe tapered threads — conical), predecessor GOST 6357-73, national standards for fittings (e.g., GOST 8944 series) and international counterparts such as ISO 228-1 / BSPP (parallel pipe threads) for design and interchangeability considerations. These related standards are commonly referenced when selecting sealing method, thread form or verifying cross-compatibility.

Keywords

GOST 6357-81, cylindrical pipe thread, parallel thread, pipe thread profile, pipe fittings, thread tolerances, interchangeability, BSPP equivalence, GOST 6211-81, pipe thread standard.

FAQ

Q: What is this standard?

A: GOST 6357-81 is a national standard that establishes the basic norms of interchangeability for cylindrical (parallel) pipe threads: its profile, principal dimensions and tolerances for external and internal cylindrical pipe threads.

Q: What does it cover?

A: It covers thread profile geometry, nominal sizes and pitches, tolerance classes and rules for mating cylindrical internal threads with external conical threads (permitted combinations and checking). It also records dimensional and manufacturing requirements to ensure interchangeability.

Q: Who typically uses it?

A: Manufacturers of pipes and fittings, piping designers and engineers, inspection and quality control personnel, suppliers of plumbing and industrial threaded components, and maintenance workshops. These users rely on the standard to ensure parts from different sources assemble correctly.

Q: Is it current or superseded?

A: The document GOST 6357-81 is listed as действующий (active / in force) in national catalogs; it was approved in 1981 and introduced into force on 1 January 1983, with later reprints and recorded updates in the national standards database. Users should check the official national catalogue for the latest amendments or expiry notices before normative use.

Q: Is it part of a series?

A: Yes — it is part of the set of GOST documents that regulate pipe threads and fittings. Closely related documents include the tapered thread standard GOST 6211-81 and earlier/adjacent GOSTs such as GOST 6357-73 (earlier edition) and other GOSTs covering fittings and thread types. Internationally, similar subject matter appears in ISO 228-1 / BSPP documents for parallel pipe threads.

Q: What are the key keywords?

A: Cylindrical pipe thread; parallel thread; GOST 6357-81; thread profile; thread tolerances; interchangeability; BSPP; GOST 6211-81; pipe fittings; sealing (sealant/gasket required).