Explosion-proof products, fasteners play an important role, we all know that flameproof electrical equipment is the use of flameproof shell to have explosion-proof performance, if the fastener in addition to what problems, then the flameproof shell and the joint surface will not match, but there are gaps or other situations, then the flameproof product loses the meaning of flameproof, so fasteners play an important role in explosion-proof products.
Below, the explosion-proof cloud platform makes a brief introduction to the requirements for explosion-proof equipment fasteners for your reference.
Fasteners typically include the following 12 categories of parts
Bolt: A type of fastener consisting of two parts, a head and a screw (a cylinder with an external thread), which needs to be matched with a nut to fasten and connect two parts with through holes. This form of connection is called bolted connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolted connection is a detachable connection.
Studs: A type of fastener without a head, only threaded at both ends. When joining, one end of it must be screwed into a part with an internally threaded hole, and the other end passed through a part with a through hole, and then the nut must be screwed on, even if the two parts are fastened together into a single piece. This form of connection is called a stud connection and is also a detachable connection. It is mainly used for the occasion that one of the connected parts has a large thickness, requires a compact structure, or is not suitable for bolt connection due to frequent disassembly.
Screws: It is also a type of fastener composed of two parts, the head and the screw, which can be divided into three categories according to the use: machine screws, set screws and special purpose screws. Machine screws are mainly used for fastening connections between a part with a tight threaded hole and a part with a through hole, and does not require nut fit (this form of connection is called screw connection, which also belongs to detachable connection; It can also be used with a nut for a fastening connection between two parts with through holes. Set screws are mainly used to fix the relative position between two parts. Special purpose screws, such as eye screws, etc., are used for lifting parts.
Nut: with internal threaded holes, the shape is generally flat hexagonal cylindrical, and there are also flat square cylindrical or flat cylindrical shapes, with bolts, studs or machine screws, used to fasten and connect two parts, making them a whole.
Self-tapping screws: Similar to machine screws, but the threads on the screws are dedicated threads for self-tapping screws. It is used for fastening and connecting two thin metal components, making it a whole, and a small hole needs to be made in advance on the component, and because this screw has a higher hardness, it can be screwed directly into the hole of the component, so that the internal thread of the response is formed in the component
Wood screws: It is also similar to machine screws, but the threads on the screw are special threads for wood screws, which can be screwed directly into the wooden component (or part) and used to fasten and connect a metal (or non-metallic) part with a through hole with a wooden component. This connection is also a detachable connection.
Washer: A type of fastener in the shape of a flat ring. It is placed between the supporting surface of the bolt, screw or nut and the surface of the connecting part, and plays the role of increasing the contact surface area of the connected part, reducing the pressure per unit area and protecting the surface of the connected part from being damaged; Another type of elastic washer can also play a role in preventing the nut from loosening.
Retaining ring: It is installed in the shaft groove or shaft hole groove of machines and equipment, and plays the role of preventing the parts on the shaft or hole from moving left and right.
Pin: Mainly used for parts to position left and right, some can also be used for parts connection, fixed parts, power transmission or locking fasteners.
Rivet: A type of fastener composed of two parts, a head and a nail bar, which is used to fasten and connect two parts (or components) with holes to make them a whole. This form of connection is called rivet connection, or riveting for short. It is a non-detachable link. Because if two parts that are connected together are separated, the rivets on the parts must be destroyed.
Components and connecting pairs: assemblies are a kind of fasteners supplied in combination, such as a combination of a certain machine screw (or bolt, self-supplied screw) and flat washer (or spring washer, lock washer); Connecting pair refers to a type of fastener that combines a combination of a special bolt, nut and washer, such as a high-strength large hexagon head bolt connection pair for steel structure.
Welding nail: a heterogeneous fastener composed of a nail rod and a nail head (or no nail head), which is fixedly connected to a part (or component) by welding method, so as to be connected with other parts.
Hidden dangers related to fasteners in explosion-proof on-site inspection
01
Explosion-proof equipment is missing fasteners.
The explosion-proof junction box lacks hexagonal bolts and does not have spring washers, which is in a state of detonation in an explosive environment, and once the combustible gas enters, it will become an ignition source. It is required that the fastening bolts of the joint surface should be complete, the spring washer and other anti-loosening facilities should be complete and intact, and the spring gasket should be flattened.
Refer to the Code for Construction and Acceptance of Electrical Installations in Explosion and Fire Hazard Environments of Electrical Installation Engineering (GB50257-2014) and the Code for Electrical Explosion-proof Safety in Hazardous Places (AQ 3009-2007).
02
Explosion-proof electrical equipment end cover fixing screws are missing.
Article 8.0.2.3 of the Code for the Construction and Acceptance of Electrical Installations in Explosion and Fire Hazard Environments of Electrical Installation Engineering (GB50257-2014): The shell of explosion-proof electrical equipment shall be free of cracks and damage, and the paint shall be intact. The junction box cover should be tightened, and the fixing bolts and anti-loosening devices should be complete.
03
The fixing bolts of the equipment in explosion-proof places are partially missing.
Clause 6.1.2.1.5 of AQ 3009-2007 of the Code for Electrical Safety and Explosion-proof in Hazardous Places: Explosion-proof electrical equipment should be installed on a bracket made of metal, the bracket should be firm, and the fixing bolts of vibrating electrical equipment should have an anti-loosening device.
The fixing bolts of the equipment in explosion-proof places are partially missing; The fixing bolt is not set to loosen: the screw is not headed
04
The fastening bolts of the explosion-proof distribution box lack anti-loosening measures.
The fastening bolts of the explosion-proof distribution box used in the explosion hazard area of an enterprise lack anti-loosening measures and are corroded, which does not meet the requirements of relevant specifications.
In accordance with clause 6.1.2.1.4 of the Code for Electrical Explosion Protection Safety in Hazardous Locations (AQ 3009-2007):
The fastening bolts of explosion-proof electrical equipment should have anti-loosening measures, and there should be no loosening and rust.
It is recommended that enterprises investigate and maintain the fastening bolts of explosion-proof distribution boxes used in explosion hazard areas in accordance with the requirements of the current code, and increase anti-loosening measures to prevent loosening and corrosion.