GB/T 43924.3-2024Aerospace - MJ threads - Part 3: Limit dimensions for fittings for fluid systems (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting:

This document is part 3 of GB/T 43924 Aerospace MJ Thread: GB/T 43924 has been published in the following parts:

--- Part 1: General requirements;

--- Part 2: Limit dimensions of bolt and nut threads;

--- Part 3: Limit dimensions of threads for fluid system piping components:

This document is modified to adopt ISO 5855-3:1999 "Aerospace MJ threads Part 3: Limits of threads for fluid system piping components" size":

A new chapter "Terms and Definitions" has been added to this document:

The technical differences between this document and ISO 5855-3:1999 and their reasons are as follows:

--- ISO 965-1 (see 7.1 and 7:2) has been replaced by the normative reference GB/T 197 to adapt to my country's technical conditions and increase the Operability;

--- Replaced ISO 5855-1:1999 (see 7.1, 7:2 and 7:3) with the normative reference GB/T 43924.1-2024 to adapt to our the country's technical conditions and increase operability:

The following editorial changes were made to this document:

---Added references:

Introduction

GB/T 43924 "Aerospace MJ Thread" is intended to consist of three parts:

--- Part 1: General requirements: The purpose is to specify the thread type and its dimensions, tolerances, markings, calculation specifications of MJ threads for aerospace applications:

Formula, etc:

--- Part 2: Limit dimensions of bolt and nut threads: The purpose is to specify the limits of bolts with a nominal diameter of 1:6 mm to 39 mm:

And the MJ thread limit size of the nut:

--- Part 3: Limit sizes of threads for fluid system pipe fittings: The purpose is to specify the MJ for aerospace fluid system pipe fittings:

Limiting thread size:

In the design of aviation and spacecraft, in order to reduce the volume and make the parts structure as compact as possible, and to withstand the impact force environment, Therefore, the threads used in structural connections have high fatigue strength and long fatigue life:

The root radius of the thread and the flattening amount of the inner thread minor diameter, the outer thread root is an arc transition, which meets the requirements of impact load and high fatigue:

It has been widely used in the aerospace field: This document improves the standards for basic fasteners of my country's aerospace products:

Aerospace MJ threads Part 3:

Limit sizes of threads for fluid system pipe fittings

1 Scope

This document specifies the limit sizes of MJ threads for aerospace fluid system fittings:

This document applies to threaded connections for aerospace fluid system piping components:

2 Normative references

The contents of the following documents constitute the essential clauses of this document through normative references in this document:

For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to this document:

GB/T 197 General thread tolerances (GB/T 197-2018, ISO 965-1:2013, MOD) GB/T 43924.1-2024 Aerospace MJ threads Part 1: General requirements (ISO 5855-1:1999, MOD)

3 Terms and definitions

There are no terms or definitions that require definition in this document:

4 Nominal diameter and thread pitch

Nominal diameter and thread pitch are shown in Table 1:

Table 1 Nominal diameter and thread pitch

Unit is mm

Nominal diameter (d or D) Pitch (P) Nominal diameter (d or D) Pitch (P) 1.25 1.5 1.5