To be honest, dry pipe compensators have been in the business for a long time, and customers often ask, "What are the advantages of your non-metallic compensators? Is it better than metal?"
I usually throw cold water first-there is no simple comparison between good and bad, these two things are not substitutes at all, they are complementary.
Look at the list of products in our site, we haveMetal hose、Universal corrugated expansion joint、High temperature axial expansion joint, there are alsoNon-metallic expansion joints (fabric fiber expansion joints)、Rectangular non-metallic expansion joint、rubber compensator、Rubber PTFE compensatorEach has its own best battlefield.
But why do non-metallic compensators appear in places such as power plant desulfurization, cement kiln tail and flue gas pipeline?
Advantage 1: Corrosion resistance, especially in wet smoke environment
After desulfurization, the pipeline behind the flue gas baffle door is acid and wet. How long do you guess the metal bellows can carry?
It is no exaggeration. According to the on-site measurement, the 316L bellows will rust through half a year to one year, and it will not last for three years if it is replaced with more expensive super duplex stainless steel.
ButNon-metallic compensatorThe main body is a fabric fiber layer with rubber or PTFE lining. Like the one in our stationRubber PTFE compensatorThe inner layer polytetrafluoroethylene is completely immune to acidic gases such as SO₂ and HCl;PTFE-lined hoseAlthough the shell is metal, it relies on PTFE lining to isolate corrosion, which is regarded as a semi-metal scheme. While pureNon-metallic expansion jointDirectly use acid-resistant rubber or PTFE as the sealing layer, and the whole section is exposed to acid mist.
To put it bluntly, carrying the advantage of corrosion, non-metallic compensator is almost the only option in the scenarios of wet desulfurization pipeline and waste incineration flue gas treatment.
Advantage 2: It absorbs large displacement and does not generate thrust
Metal corrugated expansion joints absorb displacement by corrugated deformation, but there is a fault-it will produce elastic reaction force. The greater your compensation, the greater the reaction force, the pipe support has to be thickened and reinforced, and the equipment interface also suffers.
Non-metallic compensatorWhat about the fabric and rubber rings? The rigidity is extremely low and produces little thrust. When it absorbs displacement, it is like a piece of tofu stuck to the pipe, and the bracket basically feels no extra load.
Practical cases:Rectangular non-metallic expansion jointIt is used on large rectangular sections of flue gas pipes to absorb tens of millimeters of expansion in one breath. To achieve the same compensation amount in this size, metal parts have to use multi-wave structure or hinge combination. Not to mention doubling the cost, the installation space is not necessarily enough.
You think about it, is this the truth?
Advantage 3: High temperature resistance, but different from the high temperature route of metal
How do metal expansion joints resist high temperatures? Look for heat-resistant alloys. From 304 to 310S, to Inconel, every time the temperature goes up, the price more than doubles.
Non-metallic compensatorTook another path: multi-layer composite structures. The inner layer is ceramic fiber cloth or glass fiber cloth, with heat insulation layer in the middle, and the outer layer is sealed with silicone rubber or fluorine rubber. In our stationFabric fiber non-metallic expansion jointIt is easy to use on flue gas pipelines at 700℃, but the price is one order of magnitude lower than that of metal parts with the same temperature resistance grade.
Of course, you have to remember its short board-it can't withstand high pressure. Non-metallic compensator is naturally a special product for low pressure and large displacement, and the general working pressure does not exceed 0.1MPa. If it is steam or high-pressure gas running in the pipeline, choose honestlyHigh temperature axial expansion jointOrUniversal corrugated expansion joint。
Advantage 4: Easy installation and maintenance, light weight
"In the past, to change the metal expansion joint, you had to hire a crane. Two workers couldn't install it for a day, and the downtime loss was more expensive than a piece."
Replace withNon-metallic compensatorWhat? The main body is fabric and rubber, and one person can carry it upstairs. Maintenance is simpler-instead of removing the pipe, just replace the worn rubber ring or fabric skin. From our stationrubber compensatorAndThe rubber PTFE compensator is a quick-release structure. Once the flange bolts are loosened, the old parts are pulled out and the new parts are pushed in. The whole replacement process takes less than half a day, and the downtime can be compressed to less than half a day.
You calculate this account: the hoisting cost, maintenance hours and shutdown losses saved are enough to buy several non-metallic compensators.
Advantage 5: Outstanding vibration and noise reduction effect
Metal bellows can suppress high-frequency vibration, but low-frequency vibration will be passed on honestly, and even resonance amplification.
Non-metallic compensatorThe damping properties of the rubber and fabric layers are natural advantages-like sponges, they can eat most of the mechanical vibrations and fluid pulsations. After the outlet of the induced draft fan of the power plant and the air inlet and outlet of the cement mill are equipped with non-metallic expansion joints, the jitter amplitude of the pipeline can be reduced by more than 70%, and the noise can also be reduced by several decibels.
When selecting the model, it is recommended to refer to the national standard JB/T 12235-2015. This standard clearly stipulates the parameters of pressure resistance, temperature resistance and displacement. Take the working condition parameters according to the table, and basically there will be no mistake.
After so many words, in fact, it is only one sentence:
Metals have their strengths, and non-metals have their unique skills. Find out the working conditions-is it corrosion? Is it low pressure and large displacement? Is it high temperature without pressure? Or is vibration and noise reduction priority? Whichever demand dominates, you choose which. Don't let metal and non-metal fight, let them do their own jobs, this is the long-lasting way of piping.