UNE-EN ISO 3506-2:2021

This part of ISO 3506 specifies the mechanical and physical properties of nuts, with coarse pitch thread and with fine pitch thread, made of corrosion-resistant stainless steels, when tested at an ambient temperature range of 10 °C to 35 °C. It specifies property classes in relation to austenitic, martensitic, ferritic and duplex (austenitic-ferritic) steel grades for nuts.

ISO 3506-6 provides additional technical information on suitable stainless steels and their properties.

Nuts conforming to the requirements of this standard are evaluated at that ambient temperature range. It is possible that they do not retain the specified mechanical and physical properties at elevated and/or lower temperatures.

NOTE 1 Fasteners conforming to the requirements of this standard are used in applications ranging from 40 °C to + 150 °C.

For application outside this range and to a temperature range of 196 °C to + 300 °C (see ISO 3506-6) it is the responsibility of the user to determine the appropriate choice for a given application and consulting an experienced fastener metallurgist is recommended. However, several factors need to be taken into account, e.g. stainless steel composition, time of exposure at elevated or low temperature, the effect of the temperature on the fastener mechanical properties and clamped parts, and the corrosive service environment of the bolted joint.

NOTE 2 It is intended to develop ISO 3506-5 in order to assist in the selection of appropriate stainless steel grades and property classes intended for use at high temperatures up to + 800 °C.

This part of ISO 3506 applies to nuts:

with ISO metric thread in accordance with ISO 68-1,

with coarse pitch thread M5 to M39, and fine pitch thread M8 × 1 to M39 × 3,

with diameter/pitch combinations in accordance with ISO 261 and ISO 262,

with thread tolerances in accordance with ISO 965-1 and ISO 965-2,

with specified property classes, including proof load,

with different nut styles: thin nuts, regular nuts and high nuts,

with a minimum nut height m e" 0,45D,

with a minimum outside diameter or width across flats s e" 1,45D (see Annex A),

of any shape, and

able to mate with bolts, screws and studs with property classes in accordance with ISO 3506-1.

NOTE 3 The designation system of this standard can be used for sizes outside the limits given in this Clause (e.g. D > 39 mm), provided that all applicable mechanical and physical requirements of the property classes are met.

This standard does not specify requirements for such properties as:

prevailing torque properties,

torque/clamp force properties, or

weldability.