Just recently, one of our posts talked about gasket impacting influences. Of particular interest, mention was made of UV radiation and the elements. Well, the other notable culprit in that posting was installation error. The seals we talk about here are manufactured according to a stringently imposed set of engineering specs, so they must be installed properly. To do otherwise would be to court disaster.
Geometrically speaking, the two coupling surfaces must align perfectly. If they don’t, then the bolts holes won’t line up. With that said, the two faces could still meet at a slight angle. The holes line up, but now the flanges don’t evenly compress the gasket material. An imperceptible installation error has been introduced. The distance between any two points on the two faces must be consistent all the way around the flange surfaces.
Coupling Preparation Methods
The flange surfaces must be clean and flat. No pitting can be allowed in the join site, nor can any uneven patches be allowed to exist. If they’re ignored, who’s to say how well the elastomer will compress against the metal faces? Even a seemingly insignificant patch of grime could introduce a narrow gap. Clean the joining surfaces, eliminate pitting and dirt, and inspect the surface finish for any remaining defects.
Managing Bolt Tensioning Issues
Imagine someone who has no knowledge in this field. The unskilled technician tightens every bolt, one by one, all the way down. The work looks okay, but the poorly applied torque has warped the gasket. To do this job properly, the skilled worker partially bolts each fastener, moving from side to side so that the two faces receive equal compression force. Again and again, this action is repeated. This bolting pattern must be followed. After a predetermined number of hours, apply more torque. Bolts stretch when they’re tightened, so that rest period serves a very important purpose. If the gasket and flange application call upon a sealing compound, apply the paste as directed.
Non-parallelism errors hurt the uniform application of fastener torque. These axial and radial alignment problems must be corrected before the gasket is fitted. Next, and this point is important, the material ring has to fit its provided slot inside the flange zone. Raised flange faces are an essential part of this industry, so do know the required orientation method. Finally, use a torque wrench, a tool that will precisely apply the correct quantity of torque. Used with the aforementioned bolting pattern, the faces will compress that gasket as intended so that no gaps can exist.
Inherently resilient, gaskets form lasting sealing components. Still, even this fluid-blockading property has its limits. That’s why manufacturers know so much about their wares. They collaborate with suppliers, talk to industry experts, and they know which gasket materials suit specific applications. On the flip side of that coin, there’s a corresponding dictate, a need to identify every factor that negatively impacts those materials.
Pinpointing Fluid Characteristics
Fluids are remarkable substances. They transmit force, store pressure, change state, and provide fuel. They’re also corrosive. If the liquid is highly acidic or full of alkaline vitriol, the wet stuff will seek out a weak link. Oftentimes, that weak link is a gasket. Corrosive liquids erode seal faces. Likewise, high temperatures bake material rings until they turn brittle. Furthermore, pipes conduct thermal energy. If that large energy load propagates along the pipe, it’s going to soak the conduit flanges and generate a hot spot at the gasket face.
Finally, low temperatures also threaten flexible seals. Remember, these rings are often fabricated from pliable elastomers, rings of woven or pressed material that possess an inbuilt quantity of elastic pliability. If the temperature drops low inside a pipe, then that gasket will crack and fail because this elasticity rating has been compromised. Again, material brittleness wins out.
Quantifying internalised material weakening factors:
Dealing with External Factors
If the flexible rings aren’t installed properly, they can’t perform as specified. Simply put, if these seals aren’t fitted by expert engineers, then there’s no way to assure a reliable interface coupling, one that soundly locks the pipe flanges to the inserted gasket. Environmental effects are next on the agenda. Is this some offshore facility? Maybe it’s located out in the middle of a desert? Either way, the local elements will work their way into the pipe joints. Salty deposits, ultraviolet radiation, morning temperature rises and evening temperature drops, they all affect then weaken gasket materials, even when those seals are fabricated from large chunks of reinforced sealing stuff.
There are dynamic forces in play here, with pressure variables and temperature spikes making the biggest impact on the gaskets. Even when we’re not talking about pipes, perhaps because the application concerns a geometrically dense engine block, heat and pressure are the commonest forces in play. Applied in tandem, those two influences will weaken gaskets. Chemical variances are easier to accommodate, which is just as well since highly corrosive fluids can eat right through a mechanical seal. Lastly, external factors, including UV radiation and ozone, also weaken gasket materials.