Marine Hose Clamps

Hose clamps seem simple enough on the surface – a mechanical device whose sole purpose is to hold hose or ducting firmly in place. As with most things, however, simplicity can be deceiving. Proper marine-grade hose clamps must be designed and constructed to function and last in the harsh marine environment. Many hose clamps on the market fail miserably at both. Here’s a few examples of what to look for when things head south.

Material

Most marine-grade hose clamps are constructed from high-grade stainless steel. Titanium hose clamps are also available and provide the ultimate in strength and corrosion-resistance. Though more expensive, titanium hose clamps will never rust and are both 40% stronger and lighter than their stainless-steel counterparts.

Many non-marine-grade hose clamps (such as those found in automotive and hardware stores) will feature zinc-plated or plain carbon-steel components, both of which are prone to rust and failure.

Not all stainless steel is created equal. The best choice for marine use is 316 stainless. Cheaper clamps may use 304, a lesser-grade stainless that lacks molybdenum, making them more susceptible to corrosion.

Another manufacturing issue to watch out for is a stainless-steel clamp that uses a non-stainless screw or gear housing, both of which will readily corrode.

When buying hose clamps, use a magnet to test if any non-stainless components are used. This will not indicate the quality of stainless-steel used, however. The best way to ensure you are buying quality marine-grade hose clamps is to buy only name brands from established, well-known companies.

Design

A typical hose clamp will have either a perforated band, where the screw-thread is stamped, or an embossed band, where the thread is formed into the band without cutting holes. Embossed-band hose clamps are the better choice. Perforated clamps are weaker, as the holes remove metal, reducing the strength of the clamp.

These holes create a starting point for corrosion and can also damage the hose itself when tightening the clamp. Hose clamps featuring a smooth underside and a band with beveled edges (i.e., edges that are turned or curled upward) provide the best protection against hose damage.

Another type of hose clamp is the T-bolt clamp, which features a T-bolt mechanism and hex-nut. Tightening the nut on the end of the threaded bolt forces the two T pieces toward each other, tightening the clamp. T-bolt hose clamps are more of a specialty clamp and are typically used to secure exhaust system hose or shaft log hose connections.

Installation

While hose clamps can be tightened to the proper torque using a screwdriver, the best tool to use is a nut driver, which is less prone to slipping while tightening. Never use a ratchet, which can easily overtighten the clamp and possibly damage the clamp or hose itself.

Double hose clamps should only be installed where there is sufficient length of hose barb available and hose end overlap to allow it. Hose clamps should not be installed closer than ¼-inch to the end of the hose and must fully engage the barb. A clamp that extends over the end of the barb and cuts into the hose (or forces the hose to be internally cut by the fitting) is an incorrect installation.

In such cases, if the installation of double hose clamps is required, replace the “tailpipe” (fitting) with one having a longer hose barb, or install a single, more robust hose clamp of the appropriate size. Double clamps should also be separated by at least ¼ inch (½ inch if possible) with screws located on opposite sides of the hose.