EN 24014 bolts, also known as ISO 4014 bolts or DIN 931, are a type of bolt used for fastening two or more objects. These bolts have a hexagonal head and are designed to work with hexagonal nuts. They are made of steel or stainless steel and have high strength and resistance to corrosion.
Partly threaded
DIN 931 bolts are partially threaded and have a smooth shank under the head, while DIN 933 bolts are fully threaded along the entire length of the bolt. Here are some advantages of the partial thread and plain shank of DIN 931 bolts over DIN 933 bolts:
Better alignment: The smooth shank of the DIN 931 (ISO4014-EN24014) bolt provides better alignment and positioning of the fasteners. This is especially useful when attaching parts that require very precise alignment, like flange connections. The shaft also prevents dirt deposits on the bolts.Reduced risk of breakage:
The partial thread design of the DIN 931 bolt provides better load distribution between the bolt and the adjacent material. This reduces the risk of bolt breakage, especially in applications with high loads or vibrations.Less chance of corrosion:
The smooth shaft of the DIN 931 bolt reduces the chance of corrosion compared to the full thread of the DIN 933 bolt. This is because the thread is often a breeding ground for corrosion and the smooth shaft is less exposed to corrosive environments
.Easier installation: The smooth shank of the DIN 931 bolt requires less force to turn, simplifying installation. This is especially useful when mounting in tight spaces where it is difficult to turn the bolt.
Materials
The material used for DIN 931 bolts depends on the specific application and required properties. Carbon steel is the most commonly used material due to its high strength and affordability. Stainless steel 304 and 316 are often used for applications where corrosion resistance is important. Copper and brass are sometimes used for aesthetic applications or for electrical conductivity. Titanium and aluminum are typically used for applications where a high strength-to-weight ratio is required, such as in the aerospace industry.
Material
Properties
Carbon Steel (e.g. grade 4.6, 8.8, 10.9)
Affordable, high strength, readily available, susceptible to corrosion
Stainless Steel 304
Corrosion resistant, chemical resistant, easily machinable, lower strength than carbon steel
Stainless Steel 316
Higher corrosion resistance than 304 stainless steel, resistant to acids and salt solutions, lower strength than carbon steel
Copper
Good conductivity, corrosion resistant, relatively soft, easily deformable
High strength-to-weight ratio, corrosion resistant, resistant to high temperatures, more expensive than other materials
Aluminum
Lightweight, corrosion resistant, good conductivity, low strength, easily machinable
Strength classes
The bolts come in different strength grades including 8.8, 10.9 and 12.9. The strength class is indicated by a number stamped on the head of the bolt. For example, a bolt with strength class 8.8 has a minimum tensile strength of 800 N/mm² and a minimum yield strength of 640 N/mm².
Strength Class
Field of Use
4.6
General purpose, low to moderate strength applications, non-critical structures, such as furniture and machine casings
5.6
General purpose, low to moderate strength applications, non-critical structures, such as furniture and machine casings
8.8
High strength applications, such as automotive, construction, and machinery
9.8
High strength applications requiring increased durability, such as heavy machinery and equipment
10.9
High strength applications requiring even greater durability and reliability, such as structural steelwork and heavy engineering
12.9
Highest strength applications requiring extreme durability and reliability, such as aerospace and military equipment
Ideal for use in the process industry
EN 24014, DIN 931 bolts are designed to provide high strength and are commonly used in the process industry due to their reliability and durability. Here are a few reasons why DIN 931 bolts are widely used in the process industry:
High strength: DIN 931 bolts are made of high strength steel and can withstand great loads and stresses without breaking or deforming. This is crucial in the process industry, where machines and equipment are often exposed to heavy loads and vibrations.
Reliability: DIN 931 bolts are designed to be tight and non-loosening under normal operating conditions. This reduces the risk of malfunctions and accidents that can lead to loss of production and personal injury.
Suitability for corrosive environments: The process industry often includes environments where corrosion can be a problem. DIN 931 bolts are available in a variety of materials, including stainless steel and alloy steel, which are resistant to corrosion and oxidation.
Easy replacement: If a DIN 931 bolt needs to be replaced, these bolts are relatively easy to replace. This makes maintenance and repair of equipment in the process industry much more efficient and reduces machine downtime.
Other Applications
construction
mechanical equipment
ship building
oil and gas extraction
vehicles
food industry.
Tightening torques
When installing EN 24014 bolts it is important to use the correct tightening torques. This is the amount of force required to tighten the bolts to the correct tension. The tightening torque depends on the size and strength class of the bolts and must be calculated according to the manufacturer’s specifications.
An example table of torques for a flange connection
