What exactly is a connector? To put it bluntly, it is the section where metal expansion joints (such as general-purpose corrugated expansion joints and high-temperature axial expansion joints) are connected with pipelines. Common forms include flange connection and joint welding.
Two days ago, I met a customer, who insisted that his expansion joint model was correct but couldn't be installed. It turned out that the flange standard did not match-do you think it was irritating? Before selecting the connector, find out whether the pipe interface is a national standard flange or an American standard, or whether it needs to be equipped with a guide tube. The role of the guide tube in the expansion joint is critical, it can straighten out the flow direction of the medium and avoid the bellows being directly washed. For details, refer to the article in our station[Specific Function of Expansion Joint Guide Tube]。
Selection is not a slap on the forehead, it depends on the working conditions. Temperature, pressure, medium, displacement compensation amount, none can be less.
For example, the steam pipe, you take a normal rubber compensator to carry it? That's looking for a bomb. The steam pipeline belongs to high parameters, so it is necessary to use metal corrugated expansion joint or external pressure single axial expansion joint. For example, the desulfurization flue gas system is highly corrosive, so you have to consider the special connector lined with PTFE metal hose or desulfurization flue gas baffle door. There are also metal corrugated expansion joints used in the cement industry, which are high-temperature and dust, so the sealing surface of the connector has to be wear-resistant. One more question when selecting: Is the displacement axial or transverse? What is the angular displacement? Otherwise, if you install a double hinge transverse expansion joint, the pipe only goes axially, which is a waste of money.
How many pits have you stepped on to install connectors? Let's start with the tie rod nut.
Many masters forgot to adjust the tie rod nut after installing the expansion joint, or didn't dismantle the transportation fixing screw at all. The service life of the expansion joint is cut in half directly. The correct way to do this is to confirm that the screw is removed before installation (only for non-transport fixing), and then adjust the tie rod nut according to the design drawings to leave the bellows in a pre-tensioned or pre-compressed state. Let's talk about the direction of the arrow-the direction of the arrow of the expansion joint points to the direction of the medium flow. If the guide tube is installed backwards, the bellows will be stuck, resulting in abnormal vibration and noise. When installing the expansion joint of the large tie rod, we must pay attention to the coaxiality of the pipelines at both ends. If the deviation is large, the force of the tie rod will be uneven, and the bolt will break after a long time. These details are presented in[Correct Installation Method of Large Tie Rod Expansion Joint]It's all talked about.
Wrong choice of material, two lines of tears in the later period. 304 and 316L stainless steel are commonly used for the main body of the connector, but in occasions with high corrosion resistance requirements, such as chemical industry and desulfurization, PTFE-lined or PTFE-lined compensators must be used.
The connector of PTFE-lined hose is lined with PTFE layer, which can withstand almost all strong acids and alkalis, but the temperature must be controlled at-20~200℃. If it exceeds this range, it must be pure metal. There is another situation: the connector of the directly buried (fully buried) expansion joint for directly buried pipeline should be additionally waterproof and anticorrosive, otherwise it will rust through after being buried in the soil for a few years. And guess what? In a power station project, ordinary carbon steel was selected as the connector material. As a result, it leaked half a year later, and the whole pipeline was dug and replaced, resulting in hundreds of thousands of losses.
When should I change the connector? Don't wait for a leak to be in a hurry. Generally, the life of the metal expansion joint connector is similar to that of the bellows body, but the interface is prone to problems first due to vibration or installation stress.
Regularly check the flange surface for corrosion pits, cracks in welds and loose bolts. If the gasket at the connector is found to be aging, the seal is failing, or the flange is deformed, it will have to be replaced. Gas bellows have a specified age, and the specific changes are made every few years, depending on the local gas company and national standard. However, the connectors of non-metallic expansion joints (fabric fiber expansion joints) have a shorter life because the fabric layer will age. Don't feel bad about the money. If the connector breaks, the whole system will have to stop.
In the final analysis, the connector is the 'joint' of the pipeline system. If the joint does not work well, the whole system will not work well.
When selecting the model, compare the product list in our station-metal hose, universal corrugated expansion joint, high-temperature axial expansion joint, compound hinge transverse expansion joint... each has corresponding connection mode. If you're not sure, just look at itType and size table of expansion jointOr ask customer service forMetal hose size comparison table。 It is better to spend half an hour reading the instructions before installation than repairing them for three months afterwards.