Harsh climates can damage sensitive machinery. Following on from that claim, extreme weather conditions cause damage to tough-as-nails industrial materials. And, since pipelines travel across vast open spaces, often while attacked by the most severe elemental forces, then they’re an easy target for this effect. Hot or cold, wet or dry, climate extremes can compromise a pipe, at least that’s the case if a pipe has a weak spot.

Gasket Stress: Extreme Weather Impact

Concerning that weak spot, gaskets can hardly be called fragile. They’re made of tough engineering plastics, dense fibres and durable metals. Still, think about weather-driven performance fluctuations. A hot sun directs radiated thermal energy straight at a flange. It reacts like a heat sink and absorbs the energy. Okay, the gasket material can handle the heat, but now the sun sinks. A cold night drops hard, the compressible seal contracts, and then the sun comes up again. Cyclical forces expand and contract the gasket. If this material can’t tolerate these transient energies, it’ll fail. Not right away, but the seal will eventually become inflexible, to the point that it cracks.

Materials That Can Handle Weather Extremes

Desert weather is bad, for that’s where cycling forces are at their worst. Arctic environments aren’t much better, though. What’s needed here, in both situations, is a weather-adaptable gasket family. The chosen material won’t crack when it’s chilled, nor will it harden when attacked by UV radiation. Lastly, neither ozone nor cyclical heating and cooling can cause the material to weaken. Whatever the occasion, it sounds like this is a job for a fluoroelastomer seal. Viton, a branded fluoroelastomer, can withstand high and low-temperature extremes, plus the material altering properties of both Ultraviolet rays and ozone gas. If this harsh-environment candidate doesn’t suit a specified application, a polyurethane gasket will provide an almost as capable set of weather negating features.

Essentially, thermal fluctuations are the biggest threats, but there’s also ultraviolet radiation, icy rain and ozone, too. Impressively capable, even when set upon by harsh weather conditions, Viton stays elastic when the temperature drops as low as -30°C. Better yet, especially for desert-installed seals, the synthetic rubber can tolerate 260°C of blistering heat. If Viton or polyurethane isn’t viable options, gasket designers are rarely stuck. EPDM (Ethylene Propylene Diene Monomer) rubber is yet another option. As a weather-resistant gasket material, this material makes for an outstanding cold weather candidate. Silicone is the last member of this weather beating quartet, but the story doesn’t end here, not when there are composites available that combine the best features of all of these synthetic rubbers.

A ring of bolted fasteners typically encircles a pair of flange faces. Ideally, the bolts are tightened in a pattern so that they deliver a fixed amount of torque. In this way, a pipe joint or system fitting maintains a leak-free coupling. Even if the fluid flowing through a coupling is highly pressurized, the properly tightened ring of fasteners holds firm, at least that’s the general assumption.

Rejecting Flange-Fitted Conjectures

Engineers never make assumptions. Apart from anything else, bolts suffer from torque loss hardships. Even a mere 24 hours after the tightening force has been applied, bolts and nuts will relax a little. And that’s the first pertinent causative factor, the fact that bolts don’t hold their shape. They stretch a little because heat-treated metals are tempered and malleable. If that weren’t the case, hardened fasteners would be so brittle, so frangible, that they’d fracture. To compensate for alloy malleability issues, installation technicians return to gasket fitting sites and re-torque relaxing bolts.

Concerning Gasket Creep Challenges

Less compression-capable sealing materials have trouble conforming to extreme flanging pressures. As the torque applied to a joint surpasses a gasket material’s compressibility limitations, it flattens out and loses its shape. This time around, instead of the bolts stretching, it’s the gap between those anchored fasteners that diminishes. At any rate, the effect is much the same. With that flange and gasket space contracting, torque loss problems blossom. Offsetting such challenges, gasket materials are creep tested and assigned relaxation resistance ratings. Take note, creep relaxation performance can also be influenced by in-system and environmental temperature fluctuations.

Avoiding Installation Mistakes

Wrongly applied tightening patterns complicate matters. Worsened when a technician doesn’t use a second or third re-torquing pass, bolted flanges suffer from seating stress on one side of the gasket while the opposing side presents as a low-compression sealing area. Left like this, a gasket blowout becomes a distinct possibility. Referring back to creep relaxation performance issues, thicker gaskets and more elastomeric materials are particularly sensitive to seating stress hazards. Incidentally, as another point of installation concern, pipe parallelism is a known torque loss troublemaker. If flange faces aren’t parallel, aren’t closely aligned, then a coupling’s positional characteristics will inevitably suffer.

Words like “creep” and “relaxation” become especially relevant when talking about torque loss difficulties. Subsequently, leakage and blowout conditions become high probability events. Let’s add compressibility and plasticity to the list of engineering terms. Compressibility, the way a gasket thins when it’s torque-tightened, is a factor that’s influenced by the selected gasket material and the thickness of that seal, among other things. On the other hand, plasticity problems ensue when malleable fastener metals stretch and deform.