Steel bolts

Steel Bolts

Steel bolts are threaded fasteners used with nuts and, where required, washers to create detachable joints. Typical applications include pipeline flanges, valves, supports, machinery and steel assemblies. Joint integrity depends on the correct diameter, length, property class and surface finish. Selection should therefore follow the project specification or equipment documentation rather than visual dimensions alone.

Main types of steel bolts

Hexagon head bolts are common in piping and installation work because they can be held and tightened with standard spanners or sockets. The website category structure identifies hexagon bolts marked to GOST 7805-70. Buyers should verify the specified standard: GOST 7805-70 and GOST 7798-70 use different accuracy classes, while the applicable document defines dimensional requirements.

International procurement documents may also refer to DIN 931 for partially threaded bolts and DIN 933 for bolts threaded over the length prescribed by the standard. These designations must not be treated as automatically interchangeable. Head dimensions, threaded length, tolerances and the approved project specification all require comparison before substitution.

Materials and available configurations

Carbon or alloy steel is commonly used for this fastener group; the exact steel grade must be confirmed in the product documentation. Uncoated bolts may be suitable where the environment and the assembly’s protection system permit them. Zinc coating improves resistance to atmospheric corrosion, but it does not make carbon steel equivalent to stainless steel and does not define load capacity.

Property classes 5.8 and 8.8 describe mechanical properties, not bolt size. Class 8.8 steel bolts should be specified only where required by the joint design, with compatible nuts and washers. Changing to a lower or higher class without engineering verification can alter joint behaviour.

Applications for steel bolts

Bolted fasteners are used to assemble pipeline flanges and install valves, pumps, supports and industrial equipment. Relevant sectors include water supply, heating, municipal infrastructure, manufacturing and construction. In a flanged joint, the bolt, nut and washer set generates the clamping force needed to compress the gasket. Bolt quantity and tightening sequence must follow the flange, valve or project documentation.

How to select steel bolts

Start with the required standard, nominal metric thread diameter, pitch and bolt length measured from the bearing face under the head to the end. Then check threaded length, property class, material, coating, grip length and nut-and-washer compatibility. For flange bolting, refer to the assembly drawing, valve data sheet or piping specification.

Do not select tightening torque from diameter alone. It also depends on property class, thread condition, coating, lubrication and required preload. Steel bolt pricing varies with size, configuration and order quantity. Exact characteristics depend on the manufacturer and must be verified against the documents for the specific product.

Why order from Pipeline Systems of Ukraine

Customers can request fasteners for a piping assembly and obtain guidance on compatibility with nuts, washers, flanges and valves. To support accurate selection, provide the standard, full size designation, property class, finish, quantity and service conditions. Confirm current availability, price, wholesale or retail terms and delivery options within Ukraine before placing the order.

Popular sizes

• M12
• M16
• M20
• M24

These are common search sizes, not a statement of current stock. A complete enquiry should also specify length, thread pitch, standard, property class and coating.

CTA

Send an enquiry to confirm the required size and price and to select a compatible flange-bolting set.

FAQ

What is the difference between partially and fully threaded bolts?

A partially threaded bolt has a plain shank below the head, while a fully threaded version carries thread over the length defined by its standard. Selection depends on grip length, shear-plane location and the approved joint specification.

What information is needed for a steel bolt enquiry?

Specify the standard, thread diameter and pitch, length, property class, coating and quantity. For flange bolting, include the flange or valve designation or an assembly drawing when available.

Can GOST 7805-70 be replaced with GOST 7798-70 or DIN 933?

Not without a technical comparison. Accuracy class, geometry, threaded length and tolerances may differ, so any substitution must be checked against the governing specification.

How is bolt length selected for a flanged joint?

Allow for both flange thicknesses, the gasket, washers and nut, plus the specified thread projection after tightening. Use the equipment documentation or an engineering calculation for the final size.

Does zinc coating provide permanent corrosion protection?

No. Zinc delays corrosion, but service life depends on coating method and thickness, damage and exposure conditions. Aggressive environments require a project-specific material and corrosion-protection assessment.