Overview of Pressure Vessel Equipment

1.1 Defects of in-service boilers and pressure vessels have to go through a process from generation and development to accidents. Such as cracks, corrosion and deformation of pressure components do not occur suddenly. If the technical inspection is carried out during the overhaul, that is, the internal and external inspections are carried out, the defects can be found in time, the development trend of it can be grasped, and corresponding measures can be taken to prevent the occurrence of accidents.

1.2 If the minor defects P found in the inspection of boilers and pressure vessels are not repaired in time and correctly according to the quality construction measures during the overhaul, the damage speed will be accelerated and the service life will be shortened. On the contrary, it will increase the service life of boilers and pressure vessels.

3. Defects found in boiler and pressure vessel inspection shall be dealt with in accordance with the provisions of DL612-1996 Boiler and Pressure Vessel Supervision Regulations.

This article is the author's experience and summary of implementing DL/T647-1998.

1.4 The technical inspection items in this article, as the content of leak-proof and explosion-proof inspection in the comprehensive inspection of boiler and pressure vessels, help boiler and pressure vessel inspectors to supervise and guide the leak-proof and explosion-proof inspection of power plants.

The coke residue and ash scale in the combustion chamber have been cleaned up.

3 When inspecting various holes and doors, care should be taken to prevent scalding from the high-temperature steam and water accumulated inside.

2 Safety matters for internal inspection of steam drums and pressure vessels 2.2.1 All soda water connection doors should be closed and locked. Make sure that there is no incoming steam or water before entering the steam drum or pressure vessel, then cover the pipe with a special pipe cover and then cover it with a rubber pad to prevent objects from falling into the pipe.

2.2.2 There should be good ventilation in the steam drum and pressure vessel, the internal temperature is >40°C, and the air is clean.

2.2.3 12V running lights or flashlights are used in the steam drum and pressure vessel, but the running light transformer cannot be placed in the steam drum or container.

2.2.4 When entering the steam drum and pressure vessel for inspection, there should be someone outside to supervise and keep in touch with outside personnel.

2.2.5 The tools and materials brought into the steam drum or container must be registered, and the inspectors' pockets are not allowed to have sporadic objects to prevent them from falling.

3 Technical inspection 2 Safety 2.1 Safety matters for internal inspection of boiler And the strong enough blocking plate to cut off, and the relevant valves have been closed, locked, and hung up warning signs.

2.1.2 Before entering the combustion chamber and flue, it should be fully ventilated. The furnace being repaired shall not leak into furnace smoke, hot air, pulverized coal or oil and steam, and requires 1 steam drum connecting pipe and deaerator 1.1 hanger a, upper and lower tile-shaped pads and inclined pads to be intact. b The pin nut should be tightened.

c. The lower part of the hanger supporting the steam drum should be in complete contact with the steam drum. The d support and hanger are complete, the bearing capacity is balanced and there is no rust.

a. Check the corrosion of the inner wall, and record the corrosion position, depth, shape, area, etc. The remaining wall thickness of the uniform corrosion or pitting corrosion pit is not less than the design wall thickness.

b. Take out the rust and scale cleaned from the steam drum and the down pipe or the inner wall of the container, analyze the chemical composition, determine the nature and chemical composition of the scale sample, count the total amount of scale and make a record.

c. Use an ultrasonic thickness gauge to spot-check the thickness of the cylinder wall to check for defects such as interlayers and cracks.

d. There should be no excess defects such as cracks near the opening. The inner edge of the pipe hole with a diameter of D>159 should be a rounded corner with a diameter of R>15mm, and no sharp corners are allowed.

a. The longitudinal and girth welds of steam drums and pressure vessels and the heat-affected zone shall be free of cracks and other excessive defects, and X-ray spot inspection shall be carried out at the T-joint.

b. There are no cracks and other excessive defects in the vicinity of the welding seam of the hole reinforcement ring of the head, saddle, nozzle (especially the down nozzle, feed water inlet, dosing pipe, and recirculation pipe). If there is any doubt, it must be The surface is inspected by non-destructive testing.

c. The distance between the pre-embedded parts of the steam drum and the pipe hole or the edge of the pipe hole welding seam should be greater than 50mm. d. For the parts that are monitored for operation or repaired parts, key inspections should be made, and the location, size, and nature of If the defect develops, it should be dealt with in time.

a. The connecting pipes of the steam drum (such as water level gauge pipes, pressure gauge pipes, soda water sampling pipes, dosing pipes, continuous steam exhaust pipes, sewage pipes, water supply pipes, etc.) are required to be unobstructed. If there is rust to be removed, the connected brackets should be intact, and if necessary, check whether the zero position of the local water level gauge is correct.

5. Key inspection parts of the deaerator 1. External inspection requirements of the water-cooled wall a. Irradiate with strong parallel light, and check for swelling and bulging by touching, seeing, and measuring with inspection templates.

Craftsmanship

1. The pressure vessel manufacturing process can generally be divided into: raw material acceptance process, scribing process, cutting process, rust removal process, machining (including planing, etc.) process, rolling process, assembly process, welding process (product welding test process) board), non-destructive testing process, hole scribing process, general inspection process, heat treatment process, pressure test process, anti-corrosion process.

2. Different welding methods have different welding processes. The welding process is mainly determined according to the material, grade, chemical composition of the workpiece to be welded, the structure type of the weldment, and the welding performance requirements. First of all, it is necessary to determine the welding method, such as hand arc welding, submerged arc welding, tungsten argon arc welding, gas metal arc welding, etc. There are many types of welding methods, which can only be selected according to specific conditions. After the welding method is determined, the welding process parameters are formulated. The types of welding process parameters are different. For example, manual arc welding mainly includes: electrode type (or grade), diameter, current, voltage, type of welding power source, polarity connection method, welding The number of layers, the number of lanes, the inspection method, etc.