Compensator flushing precautions: If these 5 steps are done wrong, the equipment will have to be reworked
Two days ago, I met a customer, and I called in a hurry to say that the newly installed compensator was wasted-the bellows was deflated directly after flushing, and the tie rod also collapsed. Only after asking did he know that he took the water gun for washing the fire pipe and rushed at the rubber compensator, and the pressure was adjusted to 0.8MPa. Alas, I've seen this too much. In fact, compensator flushing is not as mysterious as you think, but there are pits in every step. Today, let's break it up and crumble it, and explain these five steps clearly. You follow it and at least save money on rework.
Step 1: Find out what material the compensator in your hand is made of-metal, rubber, non-metal, and the rinsing method is completely different
Don't open the water valve as soon as it comes up. You have to look at the nameplate or the contract first to determine what the compensator is made of. If it isUniversal corrugated expansion jointOrCorrugated expansion joint for power station industryThis kind of metal is okay with pressure and temperature resistance, and ordinary water flushing is no big problem. But if you run intorubber compensatorOrRubber PTFE compensatorThen you have to be careful-rubber is afraid of oil, high-temperature water, and even more afraid of high-pressure water column.
Another category isNon-metallic expansion joints (fabric fiber expansion joints)AndPTFE compensatorTheir weak link is at the skin and flange junction. If you flush it with a high-pressure water gun, the fiber layer will be directly layered, and it will be wasted. So how to do it? First turn through the product information and see the maximum flushing pressure written by the manufacturer. If not, follow the steps below.
Step 2: Preparation before flushing-do you remove the deflector or not? Do you want to loosen the tie rod nut?
Many people will forget this step. Let's start with the deflector. We talked about it earlierSpecific Function of Expansion Joint Guide Tube-It mainly diverts flow and protects bellows. If there are impurities in the pipe (such as welding slag and rust), the impurities will get stuck between the guide tube and the bellows during flushing, wearing the bellows through. So advice: If it is the first time the new pipe is flushed, it is best to remove the deflector (provided you can remove it). If it can't be disassembled, make sure that the rinsing medium is clean and the flow rate is not too fast.
Let's talk about the tie rod nut. And guess what? Many people find that the compensator is deformed after rinsing, just because the tie rod is locked too dead. The correct way to do this is: before rinsingExpansion joint tie rod nutLoosen to the initial position when installed (generally marked at the factory) to allow the bellows to expand and contract freely. If the tie rod is used to limit the position, then loosen the nut to leave a 2-3mm gap. How exactly to adjust? You can read our previous Q&AHow to adjust the tie rod nut of expansion joint。 Remember: flushing is not a pressure test, don't use a pull rod to harness the pressure.
Step 3: Selection of flushing media and pressure-water pressure, air pressure, or chemical cleaning? How much pressure is going to be bad?
Okay, the material is confirmed, and the preparations are done. Now select media. In most cases withClearwaterJust do it, and the water temperature should not exceed 60℃. If there is oil in the pipe, consider adding a neutral cleaning agent, but remember-never use it onrubber compensatorOn, rubber is afraid of solvents. Air pressure flushing Don't use it! Unless your equipment design allows, pressure relief after compressed air is pumped in can easily bulge the bellows. How do you set the pressure? refer toMetal hose pressure standardAnd the design pressure on the nameplate of the compensator, the flushing pressure should preferably not exceed 1.2 times the design pressure. For example, a design pressure of 1.0MPaUniversal corrugated expansion jointThe flushing pressure is 0.6MPa at most, and the bellows can't stand it anymore. Pay special attention toSpecial hose for vacuumSuch thin-walled parts may deflate when the pressure exceeds 0.2MPa.
If what you encounter isDesulfurization flue gas baffle doorOrFlue gas baffle doorFor this type of sealing structure, don't flush the sealing surface with high-pressure water, which will damage the sealing strip. Just rinse the exterior with low pressure water.
Step 4: Practical points in the flushing process-sequence, flow rate and time. If one is not right, the bellows will deflate
From branch to main, from low to high. Why? Avoid backward water from heights. You flush the branch first and then open the main valve so that the dirt doesn't flush into the compensator.
How to control the flow rate? Look at the water. Don't be like a water gun. There is a critical point of laminar flow inside the bellows. If the flow speed is too fast, vortex will form, which will vibrate the bellows. A native method: put your hand on the outer wall of the pipe to feel it. Slight tremor can be done, but violent jitter means that the flow rate is too high. In terms of time, flush each section of pipe for 10-15 minutes until the water is clear. Don't be quick, I've seen people rush for half an hour, and it turns outPTFE-lined hoseA piece of the lining was washed off directly.
Special attentionLarge diameter thick wall expansion jointAndDirect buried (fully buried) type expansion jointThis kind of big guy, it is best to blow the debris in the pipe with compressed air before flushing, otherwise the rust will be blocked in the bellows trough, and you won't be able to flush it out.
Step 5: Check and reset after flushing-don't rush to turn on the machine, first see if there are any leaks or deformations in these places
After the water is finished, think it's done? That's naive. Don't rush to put the system into operation, do three things:
- Look at the leak: Focus on checking the flange connection, guide tube weld and tie rod nut root. Take a flashlight. If there are dripping traces, it means that the seal has failed. Especiallyrubber compensatorAndRubber PTFE compensatorThe rubber is easy to shrink after being blistered, and the flange gasket should be re-tightened.
- Look at deformation: Stand on the side to see whether the wave pitch of the bellows is uniform. If you find that a certain wave pitch is significantly larger than others, it is that the bellows has been washed out. You can measure it with a caliper, and if the deviation exceeds 5%, you have to change it. In additionRotary compensatorAndSleeve type pipe expansion jointHas the sealing packing of this rotating piece been flushed out by water? You will know when you look at it.
- reset tie rod: Finally, don't forget to restore the tie rod nut to working condition (that is, lock it to the design position). If this step is missed, the compensator will fail directly as soon as the system runs.
Non-metallic expansion jointIs there any blistering on the skin? Fabric fiber expansion joints will expand when exposed to water, dry and shrink again, and are prone to cracks. If you find a bulge in the skin, you have to remove it and dry it before putting it back in.
Tsk, after saying so much, in fact, the core is one sentence: find out what model of the compensator in your hand is before rinsing, and don't use general thinking to set it. If you haveDouble hinge expansion joint of air-cooled island vacuum pipeOrCompound hinge transverse expansion jointFor this special model, it is best to flip through our product information before rinsing, or ask the manufacturer directly. After all, once reworked, the labor cost and material cost add up to buy another one.