ASME B18.31.4M Standards
Scope
This Standard covers the complete general and dimensional data for metric series threaded rod recognized as an American National Standard. This Standard is applicable to both fine and coarse metric series threads of diameters from M1.6 to M56, as indicated in Table 1. The inclusion of dimensional data in this Standard is not intended to imply that all of the products described herein are stock production sizes. Consumers should consult with suppliers concerning lists of stock produc tion sizes
Dimensions
Dimensions for metric threaded rod are in millimeters and apply before coating, unless otherwise specified. Table 1 contains the thread diameter and pitch dimen sions for coarse and fine metric thread sizes considered standard.
Dimensions of metric Threaded Rods
| Nominal Diameters, D | Coarse Series Pitch | Fine Series Pitch [Note(1)] |
|---|---|---|
| M1.6 | 0.35 | --- |
| M16 | 2 | 1.5 |
| M2 | 0.4 | --- |
| M18 | 2 | 1.5 |
| M2.5 | 0.45 | --- |
| M20 | 2.5 | 1.5 |
| M3 | 0.5 | --- |
| M22 | 2.5[Note(2)] | 1.5 |
| M3.5 | 0.6 | --- |
| M24 | 3 | 2 |
| M4 | 0.7 | --- |
| M27 | 3 | --- |
| M5 | 0.8 | --- |
| M30 | 3.5 | 2 |
| M6 | 1 | --- |
| M36 | 4 | 2 |
| M8 | 1.25 | 1 |
| M42 | 4.5 | --- |
| M10 | 1.5 | 0.751 and 1.25 |
| M48 | 5 | --- |
| M56 | 5.5 | --- |
| M12 | 1.75 | 1 and 1.25 |
| M14 | 2 | 1.5 |
| M64 and larger [Note(3)] | --- |
(1) Standard fine pitch M profile screw threads of ASME B18.31M are not normally available in
threaded rod.Rods with coarse pitch threads are more commonly available than rods with fine
pitch hreads.
(2) Very limited use.
(3) Threaded rod is not normally available in these larger sizes.
Length
Overall Length
The length of the threaded rod shall be measured,
overall, from end to end.
Length Increments for Metric Threaded Rod
Threaded rod is commonly available in lengths of 1m,
2 m,and 3m but can usually be ordered in other lengths.
Thelength tolerance on threaded rods of 2 m andlonger
shall be ±10 mm and ±6 mm for nominal lengths less
than 2 m.
Ends
The ends shall be of sufficient workmanship to allow easy assembly with an appropriate mating nut.
Screw Threads
Thread Series and Tolerance Class
Threads shall be metric coarse or fine thread series
tolerance class 6g conforming to the dimensions for gen
eral purpose external threads in ASME B1.13M unless
otherwise specified by the purchaser.Thread size limits
prior to plating or coating shall be class 6g (GO and
NOT GO).After plating or coating,class 6g threads shall
be accepted using the size limits of 6g GO(high limit)
and 6g NOT GO (low limit).Threads shall be right-hand
unless left hand threads are specifically ordered. (See
section 18.)
Thread Gaging
Unless otherwise specified by the purchaser,gaging
for screw thread dimensional acceptability shall be in
accordance with Gaging System 21 as specified in
ASME B1.3.
Straightness
When required,straightness limits and the inspection technique to be used to evaluate straightness shall be as agreed upon between purchaser and supplier.
Material and Mechanical Requirements
The purchaser must specify the applicable specifica tion for the threaded rod material.The material shall meet the chemical and mechanical properties of the applicable specification.Listed below are some of the primary material specifications for threaded rod.Other materials,including non-metallic materials,may be spec ified by the purchaser.
Finish
Unless otherwise specified, threaded rod shall be sup plied with a natural (as processed) finish, unplated or uncoated, in a clean condition. Steel threaded rod shall be coated with a light oil to protect from corrosion during transportation and storage. Applicable electro deposited coatings shall be identified in accordance with ASTM F1941 M and conform to the requirements the rein. Hot-Dip zinc coating shall be in accordance with ASTMF2329. For other coated products, the purchaser shall specify the coating and thickness.
Workmanship
Threaded rods shall be visually, without magnifica tion, free from burrs, seams, laps, loose scales, irregular surfaces, and any defects affecting their serviceability. When control of surface discontinuities is required, the purchaser shall specify conformance to ASTM F 788/ F 788M for products with nominal diameters of 4mm and larger and with specified minimum tensile strengths of 800 MPa and greater.
Alloy and property class symbol and manufactures marking
Unless otherwise specified by the purchaser,the mark ing requirements specified in the material specification are optional for threaded rod at the discretion of the manufacturer. Packaging and label requirements as mandated in applicable material specifications are required
Inspection and Quality Assurance
Threaded rods shall be inspected to determine confor mance with this Standard. Inspection procedures and additional requirements may be specified by the pur chaser on the inquiry, purchase order,engineering draw ings, or shall be as agreed upon between the purchaser and supplier prior to acceptance of the order. In the absence of a defined agreement, the requirements of ASME B18.18.2 shall apply.
Coating Thickness Conformance
Unless otherwise specified by the purchaser, coating thickness and embrittlement testing conformance shall be determined in accordance with the specified coating standard. If the number of samples to be tested is not identified in the coating specification, the number of samples shall be as required by ASTM F 1470.
Material and Mechanical Conformance
Unless otherwise specified by the purchaser, coating thickness and embrittlement testing conformance shall be determined in accordance with the specified coating standard. If the number of samples to be tested is not identified in the coating specification, the number of samples shall be as required by ASTM F 1470.
Referenced Standards
Unless otherwise specified, the standards referenced
shall be the most recent at the time of order placement.
ASME B1.3, Screw Thread Gaging Systems for
Dimensional Acceptability — Inch and Metric Screw
Threads (UN, UNR, UNJ, M, and MJ)
ASME B1.13M, Metric Screw Threads—M Profile
ASME B18.12, Glossary of Terms for Mechanical
Fasteners
ASME B18.18.2, Inspection and Quality Assurance for
High-Volume Machine Assembly Fasteners
ASTM A193/A193M,Standard Specification for Alloy
Steel and Stainless Steel Bolting Materials for High
Temperature or High Pressure Service and Other
Special Purpose Applications
ASTM A 380,Standard Practice for Cleaning, Descaling,
and Passivation of Stainless Steel Parts, Equipment,
and Systems
ASTM F468M, Nonferrous Bolts, Hex Cap Screws, and
Studs for General Use [Metric]
ASTM F568M, Carbon and Alloy Steel Externally
Threaded Metric Fasteners
ASTM F738M, Stainless Steel Metric Bolts, Screws,
and Studs
ASTM F788/F788M,Standard Specification for Surface
Discontinuities of Bolts, Screws, and Studs, Inch and
Metric Series
ASTM F1470, Standard Practice for Fastener Sampling
for Specified Mechanical Properties and Performance
Inspection
ASTM F1941M,Electrode posited Coatings on Threaded
Fasteners [Metric]
ASTM F2329, Zinc Coating, Hot-Dip, Requirements for
Application to Carbon and Alloy Steel Bolts, Screws,
Washers, Nuts, and Special Threaded Fasteners