Tag: Monel K500 bolts for salt water corrosion resistance

Monel Bolts for Improved Saltwater Resistance to 316

Q: We are installing denso jackets around several steel piles at a wharf. The jackets are going to be held together by A316 stainless steel bolts. After doing a test on a few, they came back heavily corroded. Can you suggest a material that can handle the salt water?

A: To combat seawater corrosion there are two choices depending on the situation. First, is Monel 400. Monel bolts are often the go-to for salt water corrosion resistance in marine applications – even at high velocity. The Navy often uses Monel 400 for sea vessel and Monel K500 bolts when a combination of salt water resistance and high strength is needed. The only time they can show pitting and crevice corrosion is in stagnant water. The other option you have are titanium bolts. Titanium is renowned to salt water resistance and can handle both rapidly moving and stagnant waters. Titanium screws can reside in sea water for decades – up to a mile deep – without showing signs of corrosion. Both Monel and Titanium are good candidates for preventing salt water corrosion.

A4-80 vs Monel K500 Fasteners in Sea Water

Q:  For a marine project will 316SS cold worked (grade A4-80) hold up in strength pretty close to Monel K500? And what is the price comparison?
A: Thanks for contacting and good question.  The major difference is the strength and corrosion resistance. You will have decent strength of a A4-80 bolt with a min tensile of 116 KSI however K500 bolts will have around 160KSI. However even more of an issue will be the corrosion resistance in sea-water. The Monel K-500 will be immune and has no corrosion rate in sea-water, whereas the A4-80 will get attacked over time. The alloy K500 will be more expensive but if you so you have to balance the costs versus the risk of failure.