Step 1: Smooth out the work first-selection check and on-site inspection
Don't rush to unpack and unpack as soon as you come up. Let's do something about "sharpening the knife and cutting wood" first. The expansion joint in your hand is for the flue gas pipeline. The temperature, pressure and medium corrosiveness are all marked on the nameplate when the manufacturer leaves the factory. Check it against the drawings first: Are the specifications correct? YesUniversal corrugated expansion jointStillHigh temperature axial expansion joint？ Is the desulfurized wet flue gas or the original flue gas in the flue? If you choose the wrong material, for example, ordinary carbon steel is used where stainless steel bellows should be used, it will take less than two months to perforate it, and rework will be more than a matter of money.
You have to walk around the scene, too. See if the pipe brackets are firm and if there is enough space reserved for installation. When the expansion joint is hoisted, you find that the flange bolt hole is not aligned, or there is a pipe in the way next to it. Take a tape measure to measure the size of the pipe counterpart. If the deviation is large, adjust it in advance. Also, if there is dust or debris in the flue, clean it first-if this thing falls into the expansion joint, the guide tube will break as soon as it is topped.
Step 2: Unpacking and inspecting the goods, don't rush up
When the box arrives, don't swing the hammer and pry it. After unpacking, take out the product certificate and instructions, and point it one by one to the physical object. Especially for non-metallic expansion joints (also called fabric fiber expansion joints), is its skin and insulation cotton damaged? Are there any scratches or pits on the surface of the metal bellows? Are the attachments of tie rods, nuts and deflectors complete?
"Can something from the manufacturer still have problems?" Tsk, it really isn't necessarily. Two days ago, a customer found that the sealing gasket on the flange surface was deformed after unpacking. Fortunately, it was found early, otherwise it would leak when installed. Therefore, this step can't be saved-if there is a problem, go directly to the manufacturer to change it, and don't wait until the installation is finished before arguing.
Step 3: Before installation, adjust the tie rod nut and guide tube as follows
This step is where many people are prone to rollover. When the expansion joint leaves the factory, the tie rod nut is locked in order to prevent the bellows from rocking in transit. But you have to loosen these nuts before installation-note, not removing them, but loosening them into working position. How much looser exactly? Look at the cold tightness value or installation length mark on the instructions. Generally, the expansion joint is used to absorb thermal displacement. When installing, the tie rod nut should be adjusted to the half position of the compensation amount, so that it can expand and contract normally in the hot state.
In addition,guide tubeDon't reverse the direction. The function of the guide tube is to guide the flow of the medium and protect the bellows from being washed. It usually has arrows indicating the direction of flow, and the arrows must coincide with the direction of flue flow. If it is installed backwards, the smoke will directly wash the root of the bellows, and the life will be directly discounted in half. Do you think it's a loss or not?
Tips:If it is a large tie rod expansion joint, when adjusting the tie rod nut, it should be twisted symmetrically with a wrench. Don't use unilateral strength to prevent the bellows from twisting.
Step 4: Hoisting alignment, direction arrow is not a display
Before the expansion joint is hoisted, first look at the direction of the arrow on it-that arrow indicates the flow direction of the pipeline medium and also represents the displacement direction of the expansion joint. If you put it backwards, it's all wasted. Such asCorrugated expansion joint for power station industryIt is axially telescopic. If you install it into a lateral displacement, the bellows will be forced laterally and tear in minutes.
Use a soft sling when hoisting, and don't use wire rope to strangle the bellows directly. Slowly to the flange hole, the flange surfaces on both sides should be parallel, and the gap should be even. If it is crooked, don't force it with a bolt, it will deform the flange. You can pad the sheet for adjustment, or relax one side bracket first and then fine-tune it.
Step 5: Tighten the bolts with attention, don't do it recklessly
Many people think that screwing bolts is hard work, but who can't? However, the bolt tightening of the expansion joint has a torque requirement. Especially the flange connection, if it is screwed too tightly, the sealing gasket will be crushed to death, losing its elasticity, but it is easy to leak; It was screwed too loosely and loosened after running for a while.
With a torque wrench, tighten in diagonal order in 2-3 times. The moment applied gradually increases each time and finally reaches the recommended value on the instructions. If it is a metal wound gasket, don't screw it to the end at once, so that the gasket has a "rebound" process. Also, anti-jamming agent should be applied to the bolts, otherwise they will rust to death after high-temperature operation. Don't cry if you can't remove them in the next maintenance.
Step 6: Don't run after installing, pressure test and inspection are the last word
You think it's done when you're done pretending? Hehe, the real test lies ahead. Do it firstAir pressure or hydraulic testThe pressure is generally 1.5 times the design pressure. Hold the pressure for 10 minutes, and check whether there is any leakage at the flange interface, bellows weld and guide tube. Don't look with your eyes, apply soapy water or foaming agent to the weld, bubbling is leaking.
The trial is over? Don't worry, but also confirm that the tie rod nut is in a free state. Many people are nervous when testing pressure, and they lock the tie rod, so that the expansion joint can't compensate for the displacement at all. Check once: All tie rod nuts should have clearance to move, and the lock nut (loose nut) should be screwed in place.
Finally, record the installation parameters-cold tightening position, bolt torque, and pressure test results, which will all be used in future maintenance. And guess what? Some power plants forget the model when changing spare parts two years later because they don't keep records, and they have to re-measure them.
Alright, if you follow these six steps, you won't make a big mistake. Of course, there are differences in details of each product, such asrubber compensatorAndNon-metallic expansion jointThe installation requirements are different. If you are unsure, look through our product information, or ask the manufacturer directly for technology. Don't be afraid of trouble, it's more troublesome if you install it wrong.