Valve body material scope, the valve material working temperature pressure range

In choosing the valve body material, should be based on different uses and different pressure levels, to determine the valve body material suitable for working conditions.

First, the valve by valve body material classification

1, metal valves: the valve body and other parts made of metal materials. Such as cast iron valves, carbon steel valves, alloy steel valves, copper alloy valves, aluminum valves, lead alloy valves, titanium valves, Monel valves.

2, non-metallic materials Valve: the body parts made of non-metallic materials. Such as plastic valves, Tao valve, valve, FRP valve.

3, the metal body lining valve: body shape is metal, the internal surface of the main contact with the media are lining, such as lining valve, lining plastic valve, lining valve and so on.

Second, the valve body of the commonly used materials

Valve body materials and heat treatment analysis of various materials, a wide range of valve body materials, suitable for a variety of conditions.

1, gray iron, suitable for working temperature between -15 ~ +200 ℃, the nominal pressure PN ≤ 1.6MPa low-pressure valve.

2, black heart malleable iron, suitable for working temperature between -15 ~ +250 ℃, the nominal pressure PN ≤ 2.5MPa in the low-pressure valve.

3, ductile iron, suitable for working temperature between -30 ~ +350 ℃, the nominal pressure PN ≤ 4.0MPa in the low pressure valve.

4, carbon steel (WCA, WCB, WCC), suitable for operating temperature between -29 ~ +425 ℃, medium and high pressure valves, of which 16Mn, 30Mn operating temperature of -40 ~ +450 ℃, commonly used Instead of ASTMA105.

5, low-temperature carbon steel (LCB), suitable for working temperature in the -46 ~ +345 ℃ between the low-temperature valve.

6, alloy steel (WC6, WC9), suitable for working temperature of -29 ~ +595 ℃ non-corrosive medium high temperature and pressure valve; WC5, WC12 for operating temperature between -29 ~ +650 ℃ Corrosive medium temperature high pressure valve .

7, austenitic stainless steel, suitable for working temperature of -196 ~ +600 ℃ between the corrosive medium valve.

8, Monel alloy, mainly for the valve containing hydrogen fluoride medium.

9, cast copper alloy, mainly for the working temperature of -273 ~ +200 ℃ between the oxygen line valve.

The above is the valve body commonly used materials in the major categories, each specific type of material, there are many different grades, a variety of different brands and applies to a variety of different pressure levels. Therefore, the choice of valve body material, should be based on different uses and different pressure levels, to determine the needs of the working conditions of the body material.

In addition, there are titanium alloy body material ( titanium valve ), aluminum alloy ( aluminum valve ); plastic ( plastic valve ); ceramic ( ceramic valve ) and so on.

Third, the valve body rough heat treatment process

1, gray cast iron heat treatment:

For different purposes, gray cast iron can be heat treated differently after casting. Valve production gray cast iron body and other parts of the casting process is often used in the selection of heat treatment process are: eliminate the thermal stress of casting and high temperature annealing to eliminate free cementite. Thermal aging is a must. High temperature annealing is only used instead of thermal aging when casting is due to improperly controlled chemical composition and casting cooling rates, resulting in the presence of primary cementite in the as-cast microstructure.

2, carbon steel heat treatment:

Steel castings after casting has a larger casting residual stress, and sometimes cast steel parts coarse, and even overheating. These affect the dimensional stability of steel castings, reduce the mechanical properties of steel and is not conducive to the cutting process. In order to eliminate the casting stress, refine the organization, improve the mechanical properties and improve the machinability, etc., the production of carbon steel valve body and other parts in the cast after the election often use annealing or normalizing + tempering.

3, austenitic stainless steel acid heat treatment:

Austenitic stainless steel acid is the main defect is prone to intergranular corrosion, the general can take a certain amount of heat treatment of steel to prevent measures. Valve production of austenitic stainless steel body parts and other commonly used heat treatment process are: solution treatment (quenching), stable treatment and cryogenic treatment.

4, martensitic heat-resistant steel heat treatment:

Martensitic heat-resistant steel in the casting after the timely annealing to prevent cracks, and annealing time to be sufficient (usually 4 to 8 hours). The purpose of martensitic heat-resistant steel annealing is to eliminate stress, recrystallize, refine grains, reduce hardness, improve machinability, and prepare for final heat treatment.

The final heat treatment of martensitic heat-resistant steel is normalized and tempered.

5, high-quality carbon steel heat treatment:

High-quality carbon steel heat treatment 35 forged steel body, for example, 35 steel body forging to be normalized, and its final heat treatment according to the provisions of the valve manufacturing technical documents, generally to be quenched and tempered.

Fourth, the valve material application

The above is the valve body commonly used materials in the major categories, each specific type of material, there are many different grades, a variety of different brands and applies to a variety of different pressure levels. Therefore, the choice of valve body material, should be based on different uses and different pressure levels, to determine the scope of application of valve material table:

Corrosive or non-corrosive applications, temperature range up to + 425oC

Note:

CF8M is equivalent to China ZG0Cr17Ni12Mo2, corresponding to the profile of 316 stainless steel, corrosive or ultra-low temperature or high temperature non-corrosive applications, the temperature range: -268 ℃ to +649 ℃, the temperature +425 ℃ above designated carbon content of 0.04% and above

CF8 equivalent to China ZG0Cr18Ni9, corresponding to the profile of 304 stainless steel, corrosive or ultra-low temperature or high temperature non-corrosive applications, the temperature range: -268 ℃ to +649 ℃, the temperature +425 ℃ above designated carbon content of 0.04% and above

WCB is a US cast steel grade, medium carbon steel, non-corrosive applications, including water, oil and gas, temperature range: -30 ℃ to 425 ℃

HT200 China gray cast iron grades

1000WOG, 1000 refers to 1000PSI (1000PSI is equal to about 68.94kg), W