In the production of caprolactam, some pipes and equipment in the hydroxylamine post use titanium. After many years of use, the local welds appear fine cracks, causing the medium to squirt, affecting normal production. When this happens, only the fitting repair can be removed. However, it is well known that the process requirements of titanium materials are very high, and new cracks are easily generated during repair welding. If the replacement of new fittings is costly, we have used the glue repair method and achieved success.
1. Repair glue selection
The pipeline process medium is ammonium hydroxylamine disulfonate, temperature 60 ° C, pressure 0.4 Mpa. There are many types of repair glue on the market.
2. Operating process
(1) Seal the crack with an eye to make it leak (the residual pressure of the pipe at that time is 0.2Mpa).
(2) The surface of the titanium tube is sanded with sand to initially remove the deposits and increase the surface roughness to improve the bonding performance.
(3) Wash the surface with acetone or analytically pure ethanol to further remove surface grease and chemical materials.
(4) Dry, dry in hot air in winter or humid climate.
(5) Take the plugging glue A and B components and mix them evenly. Take a small amount of glue and apply directly to the crack.
(6) Apply a layer of skim glass cloth about 5 minutes later.
(7) Cover 3~5 layers according to the pressure of using a layer of glass cloth. Curing at room temperature for 8~20h, can also be cured by heating for 0.5~1h.
(1) The titanium tube repaired by this method has been running intact and has no leakage, which can solve the problem of repairing the titanium tube and save the cost for the enterprise.
(2) For pipes or equipment with a temperature higher than 100 °C, the corresponding rubber type should be selected to ensure the service life.
(3) When the pressure is plugged, it is necessary to stop the leak first and then the surface of the material.
(1) The surface treatment around the leak hole is a key step related to the success of plugging and can not be simplified. Because the presence of water, oil, and materials will destroy the structural force of the interface between the adhesive and the metal, resulting in the condition that the adhesive has solidified and the interface still has a leak path.
(2) Roughening of the metal surface can increase the contact area of the glue with the metal. In addition, the rough surface can also produce a certain mechanical bite.
(3) Glass cloth for reinforcement. The pipe fitting method should be applied to the pipe with higher pressure, and the strength effect is better.
(4) For the repair of the heat exchanger tube sheet weld, a wear-resistant rubber should be applied on the surface after repair.
(5) The optimum temperature for construction is 25 °C ~ 40 °C. When the metal surface temperature is low, it can be heated, but the initial heating temperature should not exceed 60 ° C, and it can be higher later. Because high temperature creates pores on the uncured adhesive, affecting the strength of the adhesive layer. Corresponding measures should be taken when blocking with temperature, such as thin coating of the adhesive layer, repeated scraping, glass cloth and glue construction at the same time.