What are the types of boiler hydrostatic tests? What is the purpose of a hydrostatic test?

Purpose of the boiler hydrostatic test: First, to check the tightness of the boiler’s pressure-bearing components, that is, to verify whether there are any leaks at welds, expansions, rivets, rivet joints, and on the metal surface； Second, check whether the stressed components exhibit visible plastic deformation under the test pressure. There are two types of boiler hydrostatic tests. One is the normal operating pressure test, in which the test pressure is equal to the boiler’s rated operating pressure ； Another type is a overpressure test, in which the test pressure exceeds the boiler’s rated operating pressure. Routine pressure tests can be carried out at any time, as required for the inspection and maintenance of boilers. Overpressure tests are conducted only under the following conditions: ① After the boiler is newly installed, relocated, or modified ； ②Before restarting a boiler that has been out of use for over a year ； ③The boiler’s heating surfaces have undergone major repairs ； ④Depending on the specific conditions of the boiler equipment, if there are doubts regarding the pressure-bearing components and a super-hydrostatic test is necessary

Hydraulic testing is divided into working pressure testing and overpressure testing. The purpose of a hydrostatic test is to verify the strength and tightness of pressure-bearing components. Generally, a working pressure test is carried out after the maintenance of pressure-bearing components, such as the replacement or repair of certain valves, boiler tubes, headers, etc., as well as after medium or minor repairs to the boiler. Boilers that have been newly installed, those that have undergone major repairs, and those whose heat exchange tubes have been extensively replaced should all undergo a pressure test at 1.25 times the operating pressure.

During the hydrostatic test, the pressure should be maintained for 20 minutes, in accordance with the Steam Regulations. This post was last edited by Baiyun Shanren on 2009-2-8 20:35.]

Regarding hydrostatic testing, boiler safety regulations specify clear requirements; the relevant standards can be downloaded for study*. It is generally divided into working pressure testing and over-pressure testing. However, in practice things sometimes deviate from the standards. For example, the new boilers in our company are from the American company FW; we require that hydrostatic testing be carried out at 1.5 times the pressure of the boiler drum, which is far higher than the standard requirement of 1.25 times the operating pressure of the drum. As long as the manufacturer is willing to sign off on it, conducting testing at a pressure higher than the standard is beneficial for us as users. However, for boilers that are in operation, the boiler safety regulations must still be followed to avoid having no one accountable in the event of an accident.

Hydraulic testing is divided into working pressure testing and over-pressure testing. The purposes are: ① After a boiler is newly installed, relocated, or modified； ②Before restarting a boiler that has been out of use for over a year ； ③The boiler’s heating surfaces have undergone major repairs ； ④Depending on the specific conditions of the boiler equipment, if there are doubts regarding the pressure-bearing components and a super-hydrostatic test is necessary

They are divided into pressure tests under normal conditions and hyper-pressure tests; the purpose of these tests is to check the strength and tightness of the pressure-bearing components, and they are generally carried out after the maintenance of such components.

1 Purpose of hydrostatic testing: Through hydrostatic testing, the tightness of the boiler’s pressure-bearing components is checked to ensure the reliability of their operation. For this reason, a hydrostatic test must be conducted after the boiler overhaul. 2 Key technical points of hydrostatic testing: The overall hydrostatic testing of a boiler is divided into working pressure testing and overpressure testing. Determination of the hydrostatic test pressure for boiler operation: The hydrostatic test shall be carried out in accordance with the Ministry-issued \"Standards for Hydrostatic Testing of Power Station Boilers\". For high-pressure and ultra-high-pressure drum boilers, the hydrostatic test pressure is the operating pressure of the drum ； The water pressure in the reheat system is the pressure at the outlet of the reheater. For subcritical and supercritical pressure DC boilers, low-rate forced circulation boilers, the test pressure for the primary steam system (including the evaporation section) is the pressure at the superheater outlet ； The test pressure for the reheat system is the outlet pressure of the reheater. When a shut-off valve is installed at the outlet of the separator in a low-rate forced-circulation furnace or at the outlet of the evaporation section of a DC furnace (after the separator), closing this valve allows for a hydraulic test to be conducted on the evaporation section alone. The test pressure is the operating pressure of the separator. 3 The scope of the boiler hydrostatic test generally includes all pressure-bearing components prior to the boiler’s primary valve, up to the electric main steam valve located before the turbine’s automatic main steam valve. For the reheat system, it refers to the electric valve located before the automatic main steam valve in the intermediate-pressure cylinder of the turbine, including the reheat steam supply main pipe (cold section). If there is no reliable isolation valve on the turbine side, a temporary plug can be installed to prevent water from entering the turbine. When under water pressure, the drain valve behind the electric valve should be opened to ensure absolute safety. 4 Key technical points of hydrostatic testing: In accordance with the regulations, a hydrostatic test may be carried out only after the conditions for such testing are met. The water used for hydrostatic testing should be demineralized water or water that meets the quality requirements for boiler water. It is strictly prohibited to use untreated water for pressure testing. During the hydrostatic test, the water inlet temperature should be 30 degrees higher than the metal’s brittle transition temperature, or it should be no lower than 90 degrees. It can be heated through a deaerator if necessary. During the feeding and pressurization process, the temperature difference between the upper and lower walls of the steam drum must be monitored. Safety valves with a setting pressure lower than the hydrostatic test pressure must be isolated before the test. After the boiler is filled with water, it should be inspected once before pressurization; any issues found must be addressed immediately. Strictly control the voltage rise rate. After reaching the test pressure, a thorough inspection of the pressure-bearing components is carried out. Care should be taken not to exceed the pressure limit. After the inspection, once the pressure required for the hydrostatic test is reached, the water supply for the test is cut off, and the hydrostatic test is evaluated based on the pressure drop. During the pressure reduction process, it is also possible to conduct leakage tests on the feed water control valve and the temperature reduction control valve, as well as perform pipe inspection on all drain valves. 5 Boiler overpressure test: The boiler overpressure test has an impact on the equipment’s lifespan and involves certain risks; it should be carried out carefully and with thorough planning. During testing, the plant’s boiler supervision engineer should be present to oversee the process; in the event of a suspected leak, personnel should be evacuated and the pressure reduced immediately. When the boiler meets the conditions for a pressure test, a pressure test at 1.25 times the working pressure shall be conducted. No inspections shall be carried out during the overpressure test; inspections can only be performed once the pressure has dropped to the operating pressure.

That’s absolutely correct:D :D

In line with the view from the 2nd floor, for the pressure values during hydrostatic testing and the requirements for such testing, Articles 207 and 208 of the \"Steam Regulations\" or Articles 154 and 155 of the \"Water Regulations\" shall be applied.