Shutdowns out in the industries cost millions... even when y'all plan 'em out just right. Them shutdowns get hit hard by operatin' costs from busted parts, includin' flange face imperfections, gaskets givin' out, or just plain ol' rust and corrosion. A leak can spring up right quick when corrosive stuff hits the sealin' surfaces of them facin' flanges. That right there is why keepin' up with your flange maintenance is a mighty crucial step to stop them leaks before they start.
Types of Corrosion
Flanges might go through two types of corrosion in their lifetime, I reckon. We're talkin' about aperture and pittin'.
Pittin' Corrosion
Pittin' shows up on the flange face and usually comes in groups or clusters, like a mess of bug bites. This kind of corrosion can leave little cavities or pits right there on the surface of the metal. Pickin' the right alloy from the start is one of the best ways we know to keep that pittin' corrosion away.
Crevice Corrosion
Crevice creep happens when you get a buildup of concentrated gunk right between two flanges joined together. It’s the kind of corrosion that can do a whole lot of damage 'cause it ain't easy to get in there and inspect where it's happenin'.
Right now, the main way folks check for flange damage is to take the joint apart and look at the surfaces with their own two eyes. It ain't ideal, what with the downtime and the cost. But they've been workin' on some non-destructive ways to check how bad the corrosion is without tearin' it all apart.
Ways to Prevent It
Keepin' up with your maintenance paints is one of the most common ways to help stop that corrosion. Them maintenance paints are usually urethane or epoxy-based coatings. When you're usin' 'em, you gotta put on just the right amount. If the paint's too thin, it ain't gonna do no good; but if you slather it on too thick, it'll end up sizin' up your fastenings.
There's a whole mess of different flange shapes and angles out there, and you might not be able to coat the whole thing. After you inspect the flange, you gotta put another layer of coat on it. The good thing about usin' maintenance paints is you don't need no fancy equipment or hot work to get it done.
Mechanical fixes are usually clamp encapsulated or rigid, coverin' up the flange or the empty space between 'em. These clamps or covers are made out of plastic or stainless steel and got a rubber seal built right in.
Another way to go is usin' tapes, whether they're semi-solid or full. Tapes can be made of viscoelastic polymers, wax, or petrolatum worked right into the fabric for wrappin'. These come in mighty handy 'cause them semi-solid polymers repel water real good, though you might not see 'em as much on high-pressure jobs.
Every one of these preventative methods got their good sides and bad sides—ain't no single fix that'll stop corrosion completely. But I tell you what, checkin' on 'em regular and keepin' up with maintenance can sure help stop it from rustin' out fast, so general upkeep is mighty encouraged.
Ways to Fix Corroded Flanges
There's three main ways y'all can go about fixin' up them corroded flanges:
. Addin' a polymer composite to build that flange face back up.
. Addin' material to the ring groove or sealin' face and then machinin' it back down to flange tolerance.
. Cuttin' out the busted flange and weldin' a brand new one on (that's your safest bet right there).
Things That Change Flange Corrosion Resistance While Workin'
There's three big things that mess with how well a flange fights off corrosion while it's workin'. Them are:
. How hot that corrosive agent gets
. How pure that corrosive agent is
. How concentrated that corrosive agent is
Wrap-Up
Ain't too many flange materials that suffer from stress corrosion crackin', seein' as most jobs don't run under heavy media stress. But it's sure somethin' you gotta think on when you're pickin' out your material and gasket type. When you pick the right gasket, it can do a whole lot to stop corrosion from them nasty chemicals.
There's also all sorts of different flange faces, and your gaskets gotta match up perfect with the right type of flange face. When you're dealin' with chemical oxidizers or HF acid, it's mighty crucial to pick a tough gasket that can help keep that corrosion away.
If y'all want to learn a bit more about flange corrosion, come on over and visit our website today!
