Crucial Clarifications on Product Specifications

The product page contains some generic data points that can be confusing. The following clarifications provide a precise and accurate description of this specific stainless steel product line:

• Grade Inconsistency: The “Grade” field lists both stainless steel (A2-70, A4-70) and carbon steel (4.8, 8.8) grades. For this product, only the stainless steel grades are applicable. The carbon steel grades are incorrect and do not apply.
• “Marine-Grade” Definition: The term “Marine-Grade” specifically refers to A4 Stainless Steel (Type 316). This grade contains molybdenum, an element that significantly enhances its resistance to chlorides, making it ideal for saltwater and coastal applications.
• Surface Treatment and Finish: Stainless steel is inherently corrosion-resistant and does not require a protective plating. The correct surface treatment is Plain (which typically includes passivation, a chemical process that enhances the natural corrosion resistance). The finish can be the standard matte look or Polished for a brighter, more aesthetic appearance.
• DIN 933 vs. DIN 931: The product is correctly offered in both standards to meet different engineering needs.
  • DIN 933: A fully threaded hex bolt.
  • DIN 931: A partially threaded hex bolt with a plain, unthreaded shank.

Product Parameters (Corrected and Clarified)

Understanding the Stainless Steel Grades

• A4 Stainless Steel (Type 316 – Marine Grade): The premier choice for corrosion resistance. The addition of molybdenum provides superior protection against pitting and corrosion from chlorides (salt). This makes it essential for any application exposed to saltwater, de-icing salts, or harsh chemicals.
• A2 Stainless Steel (Type 304 – General Purpose): The most common stainless steel grade. It offers excellent corrosion resistance in freshwater, atmospheric conditions, and food-grade environments. It is a reliable and cost-effective choice for applications not exposed to salt or strong chemicals.
• Strength Class (“-70” / “-80”):
  • -70: Indicates a minimum tensile strength of 700 MPa.
  • -80: A high-tensile option with a minimum tensile strength of 800 MPa.

Key Features

• Ultimate Corrosion Resistance: A4 grade offers unparalleled protection in marine, coastal, and chemical environments.
• Application-Specific Design: Choose DIN 931 (partial thread) for high-shear applications or DIN 933 (full thread) for clamping and threaded-hole applications.
• High-Strength Options: Available in A4-80 for structural applications requiring higher tensile strength.
• Hygienic and Clean: The natural finish of stainless steel is non-toxic, easy to clean, and suitable for food processing, medical, and pharmaceutical equipment.
• Aesthetic Appeal: The polished finish provides a clean, professional look for visible architectural and consumer product applications.

Appropriate Applications

• Marine & Coastal: Boat building, dock hardware, rigging, coastal construction, and any hardware exposed to salt spray.
• Chemical & Industrial: Fastening equipment in chemical processing plants, water treatment facilities, and pulp and paper mills.
• Food & Beverage: Assembling food-grade machinery, commercial kitchens, and processing equipment where hygiene and rust prevention are critical.
• Infrastructure & Architecture: Securing railings, facades, and structures in areas where de-icing salts are used or high pollution levels exist.
• Swimming Pools: Fastening ladders, lights, and other equipment exposed to chlorinated water.

Installation Guidelines

1. Select the appropriate grade (A4 for marine/chemical, A2 for general use) and standard (DIN 931/933) for your project.
2. To prevent galling (cold welding), which is common with stainless steel fasteners, apply a thread lubricant or anti-seize compound to the bolt threads before assembly.
3. Insert the bolt through the aligned holes. Use matching stainless steel nuts and washers to prevent galvanic corrosion.
4. Use a correctly sized wrench or socket to tighten the fastener. Tighten slowly and evenly to the recommended torque specification. Avoid over-tightening.