Economizer repair procedure.

Guided by the rules of Rostekhnadzor, each boiler room must have a repair log, which contains information about the repair work performed.

Repair of economizers must be carried out according to the approved preventive maintenance (PPR) schedule.

The current repair of economizers is carried out as needed, three times during the year, but at least once a year.

During current repairs, repair or replacement of worn parts and determination of the technical condition of parts or assemblies, drawing up a preliminary list of defects

Economizers are overhauled every 4 years. It is allowed to extend the period between repairs, depending on the technical condition of the economizer, if the technical condition of the economizer can ensure further economic and reliable operation.

The current repair includes inspection and detection of defects in the following units and parts of the economizer:

– external inspection with the opening of the economizer covers;
– GMO pipelines;
– flange connections;
– instrumentation;
– lining of the box (safety valve);
– connection and grounding of electrical equipment. Major overhaul includes:
– the works specified in the subsection “Current repairs”;
– replacement of pipes, coils, collectors (if necessary);
– checking of welded joints of the GMO system;
– checking the welded joints of the support beams on which the pipe sections are laid;
– condition of heating surfaces of finned tubes;
– state of appearance of the economizer;
– checking the welded connection of the duct with the economizer frame (visually);
– after repair, conduct a hydraulic test in accordance with the “Rules”;
– when installing the covers, pay attention to the seal between the pipe flanges and the gas tightness of the covers.

The control of finned tubes is reduced to:
– to the detection of cracks in the pipe body by external inspection (determined during a hydraulic test);
– determination of the heating surface of the pipe;
– during the overhaul, the thickness of the pipe wall is measured, which must be at least 4 mm.

The control of a section of finned tubes is reduced to:
– to detect leaks in the connection of pipe flanges, arcs, rolls.

If necessary, tighten the bolts, studs or replace the gasket.

It is recommended to tighten the threaded connection of the kalach in a certain order, gradually, in two or three steps. Tighten all nuts first by one third, then by two thirds, and finally by a full torque, not exceeding 70 N o m (minimum tightening torque 50 N o m).

The procedure for tightening the threaded connection of arcs with a solid flange is to be carried out to the full value of the torque not exceeding 70 N o m (minimum tightening torque 50 N o m).

– determination of the degree of contamination of pipes by external inspection, if necessary, clean;
– determination of the sealing state between pipe flanges, flanges and wall.

If necessary, seal with asbestos cord.

The determination of the sealing of covers, an arc with a branch, a knee is carried out with the smoke exhauster running, if necessary, seal with asbestos gaskets and tighten the bolts.

Check the operation of the safety valve on the box; the tightness of the valve and free rotation in the hinges must be ensured.

Checking the condition of the gas-impulse cleaning system (GPT) – pipelines, impulse chambers, damper, mixer is carried out by external inspection.

During the overhaul, all GMO welds, as well as the economizer support beams, are subjected to ultrasonic testing or another equivalent non-destructive method of flaw detection. If defects are found, it is necessary to carry out welding work by semi-automatic welding in a CO2 environment or manual arc welding with electrodes not lower than E46, followed by checking the welds.

1.3 Post-repair inspection and testing.

All boilers, superheaters, economizers and their elements after manufacture are subject to hydraulic testing.

Boilers, the manufacture of which is completed at the installation site, transported to the installation site as separate parts, elements or blocks, are subjected to hydraulic testing at the installation site.

Hydraulic test in order to check the density and strength of all elements of the boiler, superheater and economizer, as well as all welded and other joints are subject to:
a) all pipe, welded, cast, shaped and other elements and parts, as well as fittings, if they have not passed a hydraulic test at the place of their manufacture; hydraulic testing of the listed elements and parts is not mandatory if they are subjected to 100% control by ultrasound or other equivalent non-destructive method of flaw detection;
b) assembled boiler elements (drums and manifolds with welded fittings or pipes, blocks of heating surfaces and pipelines, etc.). Hydraulic testing of manifolds and piping blocks is not mandatory if all their constituent elements have been subjected to a hydraulic test or 100% control by ultrasound or another equivalent non-destructive testing method, and all welded joints performed in the manufacture of these prefabricated elements have been checked by a non-destructive testing method (ultrasound or radiography). ) over the entire length;
c) boilers, superheaters and economizers after their manufacture or installation is completed.

It is allowed to carry out a hydraulic test of individual and prefabricated elements together with the boiler, if under the conditions of manufacture or installation it is impossible to test them separately from the boiler.

5.14.2. The minimum value of the test pressure Ph during hydraulic testing for boilers, superheaters, economizers, as well as pipelines within the boiler is taken:

at an operating pressure of not more than 0.5 MPa (5 kgf / cm2)

= 1.5 r, but not less than 0.2 MPa (2 kgf/cm2);

at working pressure over 0.5 MPa (5 kgf/cm2)

u003d 1.25 p, but not less than p + 0.3 MPa (3 kgf / cm2) .

When conducting a hydraulic test of drum boilers, as well as their superheaters and economizers, the pressure in the boiler drum is taken as the working pressure, and for drumless and once-through boilers with forced circulation, the feed water pressure at the boiler inlet, established by the design documentation.

The maximum value of the test pressure is set by strength calculations according to ND, agreed with the Gosgortekhnadzor of Russia.

The designer is obliged to choose such a value of the test pressure within the specified limits, which would ensure the greatest detectability of defects in the element subjected to hydraulic testing.

Hydraulic testing of the boiler, its elements and individual products is carried out after heat treatment and all types of control, as well as correction of detected defects.

The manufacturer is obliged to indicate in the installation and operation instructions the minimum wall temperature during a hydraulic test during the operation of the boiler, based on the conditions for preventing brittle fracture.

The hydraulic test must be carried out with water at a temperature not lower than 5 and not higher than 40°C. In cases where it is necessary due to the characteristics of the metal, the upper limit of the water temperature can be increased to 80 ° C in accordance with the recommendation of a specialized research organization.

The temperature difference between the metal and the ambient air during the test should not cause moisture to fall on the surfaces of the test object. The water used for hydraulic testing should not contaminate the object or cause intense corrosion.

When filling the boiler, autonomous superheater, economizer with water, air must be removed from the internal cavities. The pressure should be raised evenly until the test pressure is reached.

The total pressure rise time is indicated in the installation and operation instructions for the boiler; if there is no such indication in the instructions, then the pressure rise time should be at least 10 minutes.

The exposure time under test pressure should be at least 10 minutes.

After exposure under test pressure, the pressure is reduced to the working one, at which all welded, rolled, riveted and detachable joints are inspected.

The water pressure during the test must be controlled by two pressure gauges, of which one must have an accuracy class of at least 1.5.

The use of compressed air or gas to raise the pressure is not permitted.

The object is considered to have passed the test if there are no visible residual deformations, cracks or signs of rupture, leakage in welded, expanded, detachable and riveted joints and in the base metal.

In flared and detachable connections, the appearance of individual drops is allowed, which do not increase in size during time exposure.

After the hydraulic test, it is necessary to ensure the removal of water.

The hydraulic test carried out at the manufacturing plant must be carried out on a special test stand that has an appropriate fence and meets the safety requirements and instructions for conducting hydrotests approved by the chief engineer of the organization.

It is allowed to carry out a hydraulic test simultaneously for several elements of the boiler, superheater or economizer or for the entire product as a whole, if the following conditions are met:
a) in each of the combined elements, the value of the test pressure is not less than the specified one;
b) continuous testing by non-destructive methods of the base metal and welded joints of those elements in which the value of the test pressure is taken less than those indicated is carried out.

2. Application of rigging schemes for the repair of heat engineering equipment and heat and fuel supply systems.

Rigging work is called horizontal and vertical movement of equipment, performed using special lifting devices. These devices are collectively referred to as rigging.

When repairing boiler equipment, rigging includes disassembly and assembly of heavy equipment components, and their replacement. Rigging also includes unloading equipment, moving it to a storage location, stowage for storage and moving it to the unit being repaired. The rigging work also includes operations for the installation of lifting devices, their equipment, verification (testing) and cleaning after completion of work.

Difficult work on lifting and moving loads during the period of equipment repairs and installation of lifting devices is usually performed by specially trained workers, called riggers. At the same time, the repairman is busy with auxiliary operations. For less complex work, a repairman independently rigs and fastens rigging devices and performs rigging operations.
Lifting cargo with jacks.

When lifting a load, rack, screw and hydraulic jacks are installed in a strictly vertical position. The head or paw of the jack rest only on the main and strong elements of the equipment being lifted. The load must rest on the entire surface of the head or foot. At the same time, measures are taken against slipping of the load from the supporting surface of the jack, for which a board is placed under the load. A board is also placed under the jack, the area of u200bu200bwhich is larger than the base of the jack.

When the load is moved horizontally (for example, when moving the base of the column), the rack and screw jacks are positioned so that the load on the rail or screw does not bend them, and the supporting surfaces of the load and the base of the jack do not slip.

If it is necessary to lift the load to a height exceeding the stroke of the jack, sleepers or specially made steel chairs are placed under the partially raised load, then the jack is released and the same lining is placed under it.

Hydraulic jacks are disassembled and inspected before each critical lift. The master checks the admissibility of applying the load from the hydraulic jack to the supporting surface.
As the load is lifted, steel half rings are placed under the piston shoulder, and in jacks with threaded washers, these washers are screwed all the way into the body so that the load does not drop quickly and hit in the event of a cuff rupture or damage to the discharge valve. At low temperatures, replace the water with thinning liquid oil to avoid defrosting the jack.

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