Boiler tubes

GB

Chinese National standards

ASME

American society of mechanical engineers

ASTM

Chinese National standards

EN

Deutsche industrie normen

DIN

Deutsche industrie normen

JIS

Japanese industrial standards

STAINLESS STEELS

– Austenitic stainless steels

The ends are vertical to the longitudinal axis and are without burrs.

Deburring applies to

Quality Assurance

We have capability and capacity to ensure boiler tube in superior condition, with advanced inspection and testing procedures, standard tests include dimensional examination, visual checking, chemical composition, mechanical properties as well as non destructive test 100% eddy current test.

Fire Tube Boiler

Fire-tube boiler is a type of boiler in which hot gas passes from the fire through one or more pipes that pass through a sealed water container. The heat of the gas is transferred through the wall of the tube through heat conduction, heating the water and eventually generating steam. Fire tube boilers are the third of the four historical types of boilers: low-pressure tank or “haystack” boilers, flue boilers with one or two large flues, fire tube boilers and high-pressure boilers with many small tubes

Water Tube Boiler

Water tube boiler is a type of boiler in which water circulates in tubes heated externally by the fire. The fuel is burned in the furnace to produce hot gas, which heats the water in the steam generation tube. In smaller boilers, the additional power generation tubes are separated in the furnace, while larger utility boilers rely on water injection tubes that make up the furnace wall to generate steam. High-pressure water tube boiler: The hot water then rises into the steam drum. Here, saturated steam is drawn away from the top of the drum.

Packing

Main products and applications

Boiler Tubes are metal tubes located inside of boilers that heat water in order to produce steam. There are two major types of tube boilers: water-tube boilers and fire-tube boilers. In water-tube boilers, water circulates inside the tubes and is heated externally by hot gases generated by the furnace. Boiler tube is installed inside boiler to heat water in order to generate steam, boiler is a closed pressure vessel designed in varieties of types, water tube boiler and fire tube boiler are main types.

• Welded boiler tubes can be supplied from stock to suit your needs
• Hot finished boiler tubes can be supplied from new production
• We can arrange cutting, deburring and testing
• Boiler tubes can be swaged/bulged to suit your requirements
• Shipping can be arranged worldwide
• Stock lengths ranging from 10200-12250mm

Process flowchart

How to get rid of surface stains of cracking tube

How to get rid of surface stains of cracking tube follow the steps below:

The first step is to clean, we must first petroleum cracking tube surface oil, dirt, grease, and some other substances removed. The second step is naturally acid, generally speaking, there are two pickling treatment, a chemical treatment, another treatment method is electrolysis, which can be handled in two ways petroleum cracking tube surface cleaning clean, but chemical pickling is a pipeline anti-corrosion measures.

The third step is necessary to use the tool to the surface of the oil cracking pipe polished, although the effect may not be very good polish, but this procedure is also indispensable. The final step is to make the surface of petroleum cracking tube jet, one can remove some of the dirt, the second is to make the roughness of petroleum cracking tube more evenly.

For petroleum cracking tube defects formed on the surface there are many, but certainly there are a lot of different reasons, the specific form of the crack is different, often found defective for its appearance on petroleum cracking tube we can see, the main reason for its main form by the following points. In fact, for the production process, the emergence of various drying phenomena of its raw materials for steelmaking summer rainy season or when it will produce up to steel gas content’s sake.

In the process, the ingot when heated due to heating of the air bubbles are burned through, it will have more cracks after the rolling, which will meet the petroleum cracking tube relatively thin, dense and sizes, its length ranging from cracks, these things collectively referred to as hairline, this is a defect. So the cause of the surface oil cracking tube defects are many, so we have to remedy. After oil cracking pipe handling, appearance becomes smoother, more beautiful. Although after the rust will not affect the use again, but if we do the work in advance, so do not bother it. We buy petroleum cracking tube among the first to note that it is not a strong corrosion resistance, have a longer life does not have to select a high-quality petroleum cracking pipe products that can reduce our future work a lot of trouble.

Characteristics of boiler pipe

Small diameter high-pressure boiler tube surface defects that affect the quality, mainly due to waste generation.

Boiler pipes often in high temperature and high pressure work, pipe smoke and water at high temperature steam oxidation and corrosion effects will occur, thus requiring durable steel with high strength, high oxidation resistance, and good organizational stability, high pressure boiler tube in addition to chemical composition and mechanical properties, hydrostatic testing done by the root, to be flaring, flattening test. Steel to heat treatment delivery. In addition, the finished steel microstructure, grain size, there are certain requirements decarburization.

High-pressure boiler tubes are seamless steel pipe categories. Seamless same manufacturing method, but used in the manufacture of steel pipe, there are strict requirements. Often in high-pressure boiler tubes at high temperature and pressure conditions of use, the tube under the effect of high temperature gas and water vapor, oxidation and corrosion will occur. Require durable steel with high strength, high resistance to oxidation corrosion, and have good organizational stability.

High-pressure boiler tube is mainly used to manufacture high-pressure and high pressure boiler superheater tubes, reheater tubes, windpipe, the main steam pipe. High-pressure boiler tubes for low and medium pressure boiler (working pressure is generally not more than 5.88Mpa, working temperature below 450 ℃) of heating surface tubes; used for high-pressure boilers (above 9.8Mpa working pressure in general, the working temperature of 450 ℃ ~ 650 ℃ between) the heating surface tubes, economizer, superheater, reheater, petrochemical industrial pipe.

Hardness testing methods of high-pressure boiler tubes

High pressure boiler tube hardness testing should take into account its mechanical properties, which is related to stainless steel as raw material for the deformation, such as punching, cutting processing performance and quality.

Therefore, all of the high-pressure boiler tubes need to conduct mechanical tests. Mechanical performance testing method is mainly divided into two kinds, one kind is tensile test, the other kind is usually hardness test.

Tensile test is the high pressure boiler tube sample, high pressure boiler tube tend to sample to the fracture on tensile testing machine, mechanical properties and determination of one or more, usually only determination of tensile strength, yield strength, break elongation, and reduction of area. Tensile test is the most basic mechanical properties of metallic materials testing methods, almost all of the metal material, as long as the requirements of the mechanical properties of the high pressure boiler tube, the provisions of the tensile test. Especially those appearance and high pressure boiler tube is not good for the material of hardness test, tensile test became the only means of mechanical properties testing.

Steam boilers

A steam boiler is a device used to create steam by applying heat energy to water.

High Frequency Resistance Welding

A continuous helical fin is attached to the base tube by high frequency electric resistance welding in order to give an efficient and thermally reliable bond. Fins can be either solid or serrated (segmented). The weld produced in this process is a true forge, blacksmith weld. This type of weld is comprised of a fusion between two portions of parent metal without the introduction of a filler material. The weld is simply produced by heating the interfaces to be joined to a plastic state and applying pressure.

Used in boilers, furnaces and fired heaters for efficient heat recovery.

High-pressure boiler tube heat defect

High-pressure boiler tubes are frequently occurs fault because of high temperatures, affecting the entire heating system, mainly due to an internal boiler for heat treatment is not perfect, a lot of heat can not be effectively converted and timely treatment.

Hardness testing methods of high-pressure boiler tubes

Heat treatment is a method of changing the physical properties of high pressure boiler pipe by heating and cooling. Heat treatment can improve the microstructure of high pressure boiler pipe, so as to meet the required physical requirements. Toughness, hardness and wear resistance are obtained by heat treatment. In order to obtain these characteristics, it is necessary to adopt quenching, annealing, tempering and surface hardening.

a. Quenching

Hardening, also called quenching, is that high pressure boiler pipe is heated evenly to the appropriate temperature, then quickly immerse in water or oil for rapid cooling, and cooling in the air or in the freezing zone. So that the high pressure boiler pipe can obtain the required hardness.

b. Tempering

High pressure boiler pipe will become brittle after hardening. And the stress caused by quenching can make the high pressure boiler pipe tapped and broken. The tempering method can be used to eliminate brittleness. Although the hardness of high pressure boiler pipe is lighter reduced, its the toughness can be increased to reduce the brittleness.

c. Annealing

Annealing is the method to eliminate the internal stress of high pressure boiler pipe. The annealing method is that the steel parts need to be heated to the critical temperature, then put in dry ash, lime, asbestos or closed in the furnace, then let it cooling slowly.

ASTM standards for Heat-exchanger and condenser tubes

How are boiler tubes made?

Both medium-pressure and high-pressure boiler tubes undergo the same initial process of manufacturing, which includes fine drawing, surface bright, hot rolling, cold drawn and heat expansion. However, the following steps are undertaken to make high-pressure pipes stronger and more resistant.

Heat treatment includes heating and cooling of the high-pressure boiler pipes which increases toughness, hardness and wear resistance. The different steps that come under heat treatment include quenching, tempering and annealing.

Quenching is done to increase the hardness of the high-pressure boiler tube. The pipe is heated evenly to an appropriate temperature and then quickly immersed into water or oil for instant cooling. This is followed by cooling in air or in the freezing zone.

Tempering is used to remove brittleness from the pipe. Quenching can cause the pipe to become tapped or broken.

Annealing can remove the internal stress in the pipe. In this process, the seamless tube is heated to the critical temperature and then left for slow cooling in ash or lime.

Rust removal of the boiler tube

There are several methods for removing rust from the boiler tube, the simplest being cleaning using a solvent and emulsion. However, this can remove only dust, oil, etc. but will not rid the pipe completely off organic remnants.

The second method is rust removal using manual or power tools. Tool cleaning can get rid of oxide coatings, welding slag and rust.

The most common method is through chemical and electrolytic methods, also known as acid cleaning.

Spray rust removal is the most ideal method for cleaning of the boiler tube as it can remove dirt, oxide and rust to a greater level. Furthermore, it can increase the roughness of the pipe.

How to choose good quality boiler tubes?

While choosing boiler tubes, look for the following to pick out the right and good quality tubes:

1. Look at the cross-section of the tube. A good quality seamless tube will have a smooth cross-section and will be devoid of bumps and irregularities.

2. Check the density of the pipe to understand the percentage of impurities in the pipe. If the pipe shows low density, steer clear!

3. Make sure you check the trademark. Reputed manufacturers always put their trademark on their seamless tubes.

4. Check the surface of the boiler tube. A good quality boiler tube will have a smooth surface. If you find the surface to be rough and uneven, you can be sure that the quality is not up to the mark.