Views:530 Author:Site Editor Publish Time: 2018-07-16 Origin:Site
According to the relevant regulations of the safety technical inspection regulations of pressure vessels and the inspection regulations for pressure vessels, a new LPG storage tank will be tested in service for less than 6 years in service for 1 years. The purpose of the test is to find and eliminate the expansion of the existing or original defects in the operation and prevent the occurrence of accidents. The LPG storage tank can be safely and reliably used in the next cycle. Secondly, some safety hazards exposed during the operation of the LPG storage tank can not be or can not be eliminated during the production period, which can only be solved through tank inspection. For example, the liquid level meter jammed malfunction, the indication is inaccurate, the first flange leaks and the fastening is invalid. Once again, through the good chance of LPG storage tank inspection, we can transform the gas, liquid and residual liquid pipes of LPG storage tank to ensure the service life of storage tanks. So LPG storage tank inspection requirements are very important for safety.
LPG Storage Tank Inspection Requirements
1. Review the loading and unloading records of LPG tanks and find out whether there is any excess filling in this cycle and the change of H2S content.
2. Macroscopical inspection
2.1 check whether the bolt number and fastening condition of the saddle support meet the requirements, whether there is enough clearance between the bolt and the long hole edge (expansion hole inspection).
2.2 check whether the saddle bearing foundation has subsidence, inclination and cracking. 2.3 check whether the sealing surface of the flange and manhole flange of the nozzle is intact, and whether there is any corrosion and damage that will affect the sealing performance.
2.4 check the corrosion at the bottom of the storage tank and the gas liquid junction, and focus on checking the corrosion of the sewage outlet and the nozzle.
2.5 check whether there is a blockage in the connecting tube of the pressure gauge and the liquid level gauge.
2.6 check whether the front end valve of the safety valve has a fully closed position locking device.
3. Surface nondestructive testing
Priority should be paid to magnetic particle testing (internal fluorescent magnetic particle testing), and inconvenient parts such as fillet welds are selected for penetration testing.
3.1 magnetic powder detection
The inner surface of the LPG tank should be cleaned and both sides of the tank should be cleaned, and the inner surface uses a fluorescent magnetic powder suspension. The ratio is implemented according to the requirements, and the magnetized region is 100mm.
(1) during the first comprehensive inspection, the inner surface should be inspected by fluorescent magnetic particle by measuring the length of the butt weld length of more than 20%.
(2) when a comprehensive inspection is conducted for the first time, the inspection personnel shall determine the detection ratio according to the macroscopic inspection.
(3) the angle joint of the nozzle, the spot of the crack, the other suspected welding joints, the repair welding area, the welding track of the working fixture, the damage place of the arc and the crack site, should be inspected emphatically.
(4) magnetic particle inspection should also be carried out if cracks are found on the outer surface. The detection ratio is determined by the inspectors according to the actual conditions.
(5) crack detection should be expanded to detect the proportion or area to detect possible defects.
4. Weld seam
4.1 one of the following conditions shall be tested by ray or ultrasonic (priority). The test ratio is determined by the inspectors according to the inspection of other items:
4.2 operation record shows overpressure or overloading phenomenon.
4.3 macro inspection found cracks;
4.4 surface nondestructive testing found cracks, and the grinding depth can not eliminate cracks after more than specified.
5. Pressure test and air tightness test