Fabrication and installation of titanium pipe
The acetic acid pipeline of a chemical plant is the most important process pipeline of the plant. The original external design of the acetic acid pipeline of a chemical plant was made of acid-resistant stainless steel (316L), but after several years of operation, the acetic acid pipeline of the oxidation section corroded seriously, and many pipes corroded and rotted through, affecting normal production and even causing accidental stoppage. The leaking acetic acid gradually corroded the nearby steel structure and equipment, seriously polluting the environment and posing a serious threat to personal safety.
After analysis of the causes of pipeline corrosion, it was found that the concentration of acetic acid in chemical plants up to 99.5%, the acetic acid molecules in the acetic acid pipeline after heating, the temperature rises, the activity increases, the corrosion of acid-resistant stainless steel pipe is serious. There are also some pipelines, although the acetic acid concentration is low, but because of the small amount of hydrobromic acid (HBr), but still caused serious corrosion of the pipeline, pipe wall thickness thinning phenomenon is serious, the chemical plant formed an accident risk to the safe production. Therefore, since 1997, the 316L acid-resistant stainless steel pipe of the chemical plant has been gradually replaced by titanium pipe, which has been operating very well for more than 4 years after the replacement, creating good conditions for the safe, stable, long, full and excellent operation of the chemical plant. This paper mainly elaborates on the production, installation process and the technical elements of the titanium pipe.
Quality inspection of titanium pipe
Table of Contents
After the arrival of the titanium pipe should be organized owner, construction manager, construction workers, quality inspectors, welding technicians, the pipe and valve parts material, specifications, quantity, quality and quality certification documents for inspection. The pipe must have the manufacturer’s factory certificate of conformity and quality certification. And should be measured one by one outside diameter, wall thickness, its outside diameter, wall thickness, ellipticity must meet the specification requirements. The inner and outer surfaces should be smooth, clean, and free of defects such as pinholes, cracks, folding, over corrosion.
Transportation of titanium pipe
Titanium tubes should be placed according to the same requirements during transportation. In the lifting process, it is advisable to use nylon or synthetic fiber sling. If steel wire rope and unloading buckle are used, they should not be in direct contact with the pipe, and rubber or asbestos products should be used to isolate them.
Fabrication of titanium pipe
The titanium pipe with good material, the smaller caliber, it is better to turn the bevel on the lathe, the lathe speed should be slower, and pay attention to cooling. Larger diameter (DN100 or more), it is appropriate to use the grinding machine to polish the bevel. The speed of operation should be slower, finished in several times, and pay attention to cooling. When close to the requirement, remove the pollution layer with a fine tooth file until the beveling requirement is reached. The bevel surface should be flat, no cracks, heavy skin phenomenon, and thoroughly remove burrs, melt ballast and oxides. The bevel angle should meet the welding process requirements, when the bevel processing is finished, pickling and cleaning within 50mm on both sides of the bevel. Then seal it with plastic cloth and mark it well. When grinding and cutting is used, the operation should be carried out in other places that meet the requirements. After the bevel processing meets the requirements, then move to the prefabricated special place.
Installation of titanium pipe
Titanium pipe construction often encounters some small holes such as condensation discharge, emission, instrumentation taking source parts, which are difficult to open with conventional methods. Before the titanium tube welding, the size of the hole and the detailed and accurate location of the hole are drawn on the corresponding titanium tube. Use a lathe to drill many small holes along the centerline of the edge of the hole, the denser the better. After all the holes are drilled, use a copper hammer to lightly hit the center of the hole arc plate to detach it, and then use a special tool such as a fine tooth round file to process the holes to meet the requirements.
Welding of titanium pipe
Titanium tube surface impurities such as oil, oxide film can be harmful to welding, must be cleaned before welding, all welding surface and the surface of the base material on each side of the weld, at least 50nrn range with a non-inducing wire brush to remove impurities, the surface of the titanium tube with oxide layer to remove the oxide film, and then the base material with acetone for cleaning. Weld wire must also be similarly cleaned, after processing the welded parts and wire should be immediately grouped welding, if placed for more than 2h, the above process must be repeated to clean up again. At the same time the operator must wear clean gloves during the welding process, the welding environment should be clean, wind direction wind suitable to reduce the dust in the air to protect both sides of the bevel and the clean wire.
Source: China Titanium Pipes Manufacturer: www.titaniuminfogroup.com