Hot-Dip Galvanized Bolts

Advantages

	Portland Bolt	Big Tank Galvanizer
Specialize in fasteners and custom requests
High-speed spinner for threaded fasteners up to 11 feet
Prefers galvanizing structural steel 20 feet and longer
3-day standard turnaround
100% quality checked
System designed for trouble-free nut fit

Process

Preparation and Cleaning

• Headed bolts are wheelabrated to remove any excess hot forging scale, while non-headed bolts may skip this process.
• The bolts are submerged in a caustic soda solution which removes organic material like cutting oil, and then quickly rinsed in water.
• Next, the bolts are submerged in sulfuric acid to remove the hot rolled scale and etch the surface of the steel. This allows the zinc to more easily penetrate the surface layer of the fastener. Again the bolts are rinsed.
• The final preparation phase requires the bolts to be submerged in a flux solution which facilitates the reaction of the zinc to the steel.

Hot-Dip Galvanizing

• The coating process involves completely immersing the bolts in a tank containing 70 tons of 840°F molten zinc. The material will remain in the tank until the zinc has metallurgically bonded to the steel. This time varies depending on the diameter, steel grade, and a number of other factors.
• A crane lifts the material while the zinc is still liquid and a high-speed spinner functions like a centrifuge to remove the excess zinc from the threads. This produces the highest quality threads and trouble-free nut fit.

Inspection and Packaging

• Parts are water cooled to solidify the zinc and to allow immediate handling.
• Each bolt is inspected to ensure all fasteners will take nuts and you will not experience installation nightmares in the field. Product is packaged professionally and clearly labeled for easy identification.

Technical Information

Galvanizing FAQ

• Galvanizing High Strength Bolts - Learn the reasons why some high strength fasteners cannot be hot-dip galvanized.
• Galvanized Nuts Tapped Oversize - Galvanized nuts are required to be tapped oversized to account for the added zinc.
• Rotational Capacity Testing - This test is required for ASTM A325 structural bolts to make certain a nut will not gall and that the assembly will develop the pretension load desired.
• Weight Gained from Galvanizing - An explanation of how much a bolt and steel plate weight increases from the zinc added during galvanizing.

ASTM Specifications

• ASTM A153 - The A153 specification covers zinc coating (hot-dip) on iron and steel hardware.
• ASTM F2329 - This is a newer specification developed in 2005 covering the requirement for hot-dip galvanizing of bolts, screws, nuts, washers and other threaded fasteners.

Benefits

Galvanizing offers an exceptional protective coating for steel fasteners. The process provides durability, long service life, and is economical in comparison to other coating options. Portland Bolt's unique system developed specifically for threaded fasteners ensures quality threads and a trouble-free nut fit.

• Hot-dip galvanizing offers long-term protection for fasteners and other steel products.
• Parts are evenly coated for complete coverage.
• Expected service life can exceed 30 years.
• Low life-cycle cost makes galvanizing an economical method of protecting steel.
• Zinc bonds metallurgically to steel providing permanent protection.