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Why do Stainless Steel Fasteners Lock Up?

May. 07, 2020

As a Railway Fastening System Supplier, share with you. Stainless steel fasteners also refer to stainless steel screws, which are national standard screws. The reasons for frequent lockups are as follows:

1. If the product is not selected correctly, you should confirm whether the mechanical properties of the product can meet the use requirements before use. In addition, the length of the screw is properly selected, and one or two pitches of the nut are exposed after tightening.

2. Rough teeth or foreign objects. If there are solder joints and other metal shavings are caught between the teeth, it will often cause locking.

3. Too much force or too fast locking speed. Use a torque wrench or socket wrench as much as possible. Avoid using an adjustable wrench or an electric wrench. Because the electric wrench often causes the locking speed to be too fast, the temperature rises rapidly and locks up.

4. The wrong angle of the force application direction. The nut must be screwed perpendicular to the axis of the screw, not tilted.

5. The use of unused flat and spring washers can effectively prevent the problem of over-tightening.

Screw Spike

Screw Spike

Screw Spike failure hazards and anti-corrosion measures

Compared with other bolts and screws, stainless steel bolts and stainless steel screws are more widely used in low temperature and high temperature parts, so stainless steel screws are more and more commonly used in actual use.

1. The hazard of stainless steel screw failure.

In general, carbon steel and alloy steel bolts fail when there are obvious corrosion products and thinning on the surface, and stainless steel screws will lose strength without seeing any changes on the surface, causing serious damage to the structure or equipment. Its failure is more concealed and harmful.

2. Anti-corrosion measures for stainless steel screws

1. Use qualified stainless steel screws to avoid gaps in the structural design and avoid geometric conditions that are prone to surface deposition;

2. The stainless steel screws are effectively isolated from the Cl-containing aqueous solution, and the gaps cannot be avoided. The introduction of the anti-corrosion effect of stainless steel screws should be understood by welding or filling the gaps so that the aqueous solution cannot enter;

3. Adopt stainless steel material with high chromium and high molybdenum, especially in low temperature tank area, spherical tank area, and severe stress corrosion area, use good corrosion resistance steel, the effect is better.

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