April 2012 Issue
Finding Good Hose Clamps
Take a magnet along when you go clamp shopping
In the December 2011 article, “Maintaining Stainless Steel,” you mention that there are hose-clamp makers that get the stainless-steel combination right, but never shared who those manufacturers might be. I’d love to know who’s your pick!
Relative Wind, Catalina 27
We’ve evaluated dozens of hose clamps over the years—and suffered our share of corrosion failures in use. These past experience have left us with two hose-clamp mantras: Not all clamps are created equal, and never go clamp shopping without a magnet.
Some years ago—following numerous reader complaints of corroded hose clamps—we examined a handful of random “stainless” clamps from Ideal, DPC Co., Murray, Wittek, DuPage, Tridon, Gold Seal, and EEZE. Since all carried claims they were “stainless” or “all stainless,” we used a strong magnet to determine which were austenitic, ferric, or martensitic. Of the 10 clamps tested, only four passed the magnet test: two DPCs clamps, one EEZE, and one Gold Seal. In each failure, the perforated band was not magnetic, but the adjusting screw was—and when the screw corrodes, it’s game over.
The bottom line was that buyers have a 40-percent chance of getting quality, stainless hose clamps, despite makers’ claims. Lesson learned: Buy hose clamps from a local chandlery so you can inspect them before buying, and take a good magnet along for the task; be sure to check the band, housing, and the screw. It’s an easy and reasonable—but not foolproof—test that gives you better chances of avoiding early clamp failure.
Clamps made with inferior stainless (usually 400) or other metals will stick to the magnet. Good-quality stainless (300+) will be non-magnetic or nearly non-magnetic, and the best-quality clamps will be made with 316 stainless and won’t be magnetic at all.
In response to our magnet-test findings, a representative from the Ideal Division of Epicor Industries wrote us, explaining that “cheap hose clamps are not good…good hose clamps are not cheap”—worthwhile advice, straight from the horse’s mouth.
In a followup look at hose clamps, we used a screwdriver and torque wrench to force failure in an inexpensive clamp from Norton and a more expensive one from AWAB. Both 7/8-inch clamps passed the magnet test, but the Norton featured a perforated band while the AWAB had a band with pressed ridges in the metal that did not go all the way through. According to AWAB, these teeth offer a better fit on hoses than the punched-hole bands, and because there are no holes in the band, there’s more material to carry the loads.
In our torque-to-death test, the Norton’s screw housing failed with 7.5 foot pounds of pressure, the same amount of squeeze that flattened the threads of the AWAB.
While that test left us with no clear winner, the AWAB hose clamps have a good reputation in the industry for being high quality and comparatively trouble free. The maker claims its marine clamps are all 316 stainless, and our examinations have supported the claim.
Practical Sailor contributor and marine consultant Steve D’Antonio (www.stevedmarineconsulting.com) recommends the AWAB hose clamps for onboard applications, as does noted marine author and boatbuilder Nigel Calder. D’Antonio said that they have a slight design edge over others. (His website features several good articles on hose clamps.)
Your best bet is to use all 316-stainless hose clamps (AWAB or other proven brand) and to be sure you install them properly and maintain them regularly. We recommend using two hose clamps where possible, with the first one set a quarter-inch from the hose end. (The American Boat and Yacht Council requires two clamps on wet exhaust systems.) Never overtighten the screws as that will damage the housing or threads.
It’s also a good practice to regularly inspect all hose clamps, at least every three to four months. Replace any clamps that show signs of corrosion.
We’re putting together a new test of stainless-steel hose clamps. Look for that report in the near future.