General requirements for fasteners of explosion-proof equipment

General requirements for fasteners of explosion-proof equipment

1.1 To ensure that the particular explosion-proof type or to prevent contact with exposed electrically charged parts of the fasteners necessary to allow only the use of tools (such as screwdrivers, wrenches, etc.) can be loosened or removed.

1.2 Fasteners for housings containing light metal may be made of light metal or non-metallic material if the fastener's material is suitable for the housing material.

1.3 Screw holes may be tapped in the housing only if the shape of the threads is suitable for the housing material for the installation of covers that may be opened in the course of work.

Requirements for special fasteners

Thread pitch, tolerance fit, bolt (nail) head, or nut should meet the requirements of the relevant standards.

2.1 The pitch of the thread should be in line with the requirements of large pitch metric threads, from the provisions of the standard thread series preferred, the nominal diameter range of 1mm ~ 64mm; thread tolerance should be in line with the 6g / 6H (the number indicates the tolerance level, the higher the accuracy of the value of the smaller; the letter indicates that the position of the tolerance band, the external thread with a lowercase letter, the internal thread with a capital letter).

2.2 Standard parts in line with the standard requirements

2.2.1 Hexagonal bolts should meet the requirements of ISO4014 or ISO4016,DIN933,DIN931, ASME/ANSI B 18.2.3.5M, ASME B 18.2.1.

2.2.2 Hexagon socket cheese head screws shall meet the requirements of ISO467, DIN912, DIN251, DIN798, DIN4762, etc..

2.2.3 Hexagon socket set screws shall conform to ISO4026, DIN913, ASME B 18.3 (flat end), ISO4027, DIN914, ASME B 18.3 (cone end), DIN926, ISO4028, DIN915, ASME/ANSI B 18.3, JIS B 1177 (cylindrical end) or DIN438, ASME/ANSI B 18.6.2, ISO4029, DIN916, ASME B 18.3 (concave end).

When bolt (nail) heads or nut fasteners are used, the explosion-proof equipment should be marked with an "X," these fasteners should be specified in the product instruction manual, stating that they can only be replaced with the same fasteners. For high-quality screws fasteners and professional technical support, don't hesitate to contact us at adelajonly@gmail.com or visit our website at [Juxin Fasteners]: https://www.juxinfasteners.com.

2.3 Requirements for memorable fastener holes

2.3.1 Special fastener holes shall be permitted to engage a thread depth h equal to the outside diameter of the fastener threads—allowable thread depth h for memorable fastener holes.

2.3.2 The thread tolerance of memorable fastener holes shall be by 6H and meet the following conditions.

a) The bolt head should be by the lower face hole is not greater than the size of the H13 medium assembly requirements; that is, in Figure 2, part c clearance should not be greater than the H13 medium assembly allows the maximum clearance (such as M6 bolts with the hole diameter should not be greater than Ф6.6). Bolt head lower face hole and bolt fit clearance.

b) Fine rod bolt head (or nut) below the hole should be tapped to ensure the bolt does not fall off. The size of the screw hole shall be such that the contact area with the connected part is at least equal to the "X" ring contact portion of the contact area of the non-fine rod bolt in the light hole). The contact size X of the thin rod fastening bolt with the connected part shall not be smaller than the contact size of the fully threaded fastening bolt—the contact surface of the head of the fine-stemmed fastening bolt with the fastened part.

2.4 Requirements for hexagon socket set screws

Hexagon socket set screws used for fastening threaded caps (e.g., for anti-loosening purposes) shall have a thread tolerance fit of 6g / 6H and shall not protrude from the screw hole after fastening.