Why do you need a theoretical weight table? Anyone who has worked in engineering knows
Non-metallic compensators are not as regular as metal parts-the density of fabric fibers, rubber and PTFE is different, and the weight of rectangular non-metallic expansion joints and round non-metallic expansion joints of the same size can be quite different. Procurement quotation, logistics and transportation, installation and lifting point design, all of which are inseparable from weight data. The theoretical weight table is to give you a reliable reference benchmark, saving you from turning over the drawings and weighing the samples for every project. Think about it, the on-site hoisting crane has been called, and it turns out that the actual weight is 20% heavier than the estimate, so you can't be blind?
Several Key Factors Affecting Weight
The first is the superimposed thickness of the host material-the fabric fiber layer (silicone cloth, fluorine cloth, ceramic fiber cloth) and the rubber/PTFE liner. For the same area, the area density of silicone cloth and fluorine cloth can be two or three kilograms different. The second is the type of structure – single or multi-layer? Is there an insulating cotton sandwich? The temperature level is different, the thickness of the insulation layer is twice the difference, and the weight is directly doubled. The third is the way of flange connection-angle steel flange, flat flange or flange with sealing groove? The flange alone can account for 30% to 50% of the total weight. In addition, do not underestimate the accessories such as reinforcing ribs and guide tubes. A guide tube can weigh as little as two or three kilograms and more than ten kilograms.
How to calculate theoretical weight?
According to JB/T 12235-2015 standard, the theoretical weight of non-metallic compensator = skin deployment area × area density + flange skeleton weight + attachment weight. The area density of the skin has to be asked by the supplier for specific parameters, generally from several kilograms to more than ten kilograms per square meter. For your reference: The round non-metallic expansion joint of DN500, a conventional four-layer fabric structure, weighs about 25-35 kg in theory, depending on the number of layers and material grade. Here is a key point: the skin area is not a simple cross-section perimeter multiplied by length, and the margin of wave height and compensation amount must be considered. Otherwise, the calculated area is too small, and the weight will deviate.
Take the product on our site as an example
Rectangular non-metallic expansion joint, section size 1200×800mm, compensation amount ±50mm, supporting angle steel flange. According to the theoretical formula, the skin area is about 2.5㎡, the area density is 8kg/㎡, the flange angle steel L75×7 is 8 meters, the weight is about 40kg, and the total weight is about 63kg with bolts and gaskets and other accessories. The actual weighing result is 62.5kg, with an error of less than 1%. Therefore, the premise of reliability of the theoretical table is that the material parameters are accurate. If you have specific non-metallic compensator models on hand (such as the rubber compensator and fabric fiber expansion joint on our station), go directly to the sales for the measured data, which is worry-free than calculating the theoretical value.
Common misunderstandings to be aware of
First, don't think about the weight of metal expansion joints to non-metallic parts-the metal wall thickness is uniform, and the number of non-metallic layers and the texture direction of the fabric will affect the final weight. Second, the temperature level is different, the thickness of the insulation layer is twice the difference, and the weight is directly doubled. Third, the theoretical weight is in the dry state, and the skin will increase in weight by 5%-10% after moisture absorption in the field operation, so a margin must be left during hoisting. Two days ago, a customer selected a spreader according to the theoretical table. As a result, when installing it, he found that the compensator was 8% heavier than expected, and he almost had an accident. Alas, this really shouldn't have happened.
To summarize
The theoretical weight table is a tool, not a truth. It's okay to use it for budgeting and selection, but in the end, you have to confirm the actual product parameters with the supplier. In the end, this business is about accuracy and reliability. The weight of a piece of skin is poor, and the stress analysis of the whole pipe system has to be done over. If you are selecting a model for a certain project, you may wish to compare the product information on our site-whether it is a rectangular non-metallic expansion joint, a circular baffle door or a rubber PTFE compensator, there are corresponding technical parameters to check.