How to choose boiler tubes

What is a boiler tube?

Boiler tube is a type of seamless steel tube, which shares the same production technique –hot rolled or cold drawn. It can be both of carbon steel and alloy steel. There are low &medium pressure boiler tube and high pressure boiler tube as per the temperature of the applied conditions.

Size of boiler tube Uses of boiler tubes Quality problems of Boiler tubes
Types of boiler tubes Standard of boiler tube What is boiler pickling
Low and medium pressure boiler tube Characteristics of boiler pipe How to choose boiler tubes
High pressure boiler tube Manufacturing Process of Boiler Tube

boiler pipe - How to choose boiler tubes 

Size of Boiler Tube

Diameter (OD) [mm] Wall (WT) [mm] Length (L) [m]

  • OD < 60,3 5 – 6
  • OD => 60,3 WT < 7,1 5 – 6 or 10 – 14 after an agreement 22,4
  • WT => 7,1 5 – 6

Types of the length of supplied tubes: (a) random, (b) fixed ± 500 m, (c) exact + 15 / – 0 mm.

  1. Boiler tube straightness. Straightness deviation for the whole length of a tube can not exceed value of 0.0015 x L. In conversion to the 1 meter length it can not exceed 3 mm.
  2. Ends of the boiler tubes.The ends of the tubes are vertical to the longitudinal axis and are without burrs.
  3. Condition of the tubes surface.The tubes condition corresponds to the requirements of appropriate standards, heat treatment to the way of tube manufacturing and chemical composition of steel.
  4. Marking of the tubes and tube bundles.The tubes with the outside diameter up to 51 mm are marked with a label that is attached to the bundle. Larger tubes are marked at least at a one end of a tube by the necessary data.
  5. Surface protection of the boiler tubes.While ordering, it is necessary to agree upon the way and means of temporary protecting the surface of the tubes during transportation and storing. The tubes may be supplied without temporary preservation of the surface, or with the preservation of the surface with an agreed upon preservative.
  6. Packaging of the boiler tubes.The tubes are supplied in packages with a circular or hexagonal diameter with weight of 300 to 3500 kilograms. The tubes are bound with a steel band. It is possible to arrange wrapping to plastic sheet, burlap or to wooden crates.

Types of boiler tubes

The manufacturing method of boiler tube is the same as that of the seamless pipe, but there are strict requirements for the steel used in the manufacture of the steel pipe. According to the use temperature, it can be divided into two types: low and medium pressure boiler tube and high pressure boiler tube.
The mechanical properties of the boiler tube are important indicators to ensure the final performance of the steel (mechanical properties), which depends on the chemical composition of the steel and the heat treatment system. In the steel pipe standard, tensile properties (tensile strength, yield strength or yield point, elongation), hardness and toughness indexes, and high and low temperature properties required by users are specified according to different use requirements.

  1. The general boiler tube use temperature is below 350 °C, and the domestic tube is mainly made of 10 or 20 carbon steel hot rolled tube or cold drawn tube.
  2. High pressure boiler tubes are often used in high temperature and high pressure conditions, and the tubes are used in high temperature flue gas and water vapor.

Oxidation and corrosion occur when used. Steel pipes are required to have high durability, high corrosion resistance and good structural stability.

Low and medium pressure boiler tube

low and medium pressure boiler tube refers to used in low-pressure boiler (pressure is less than 2. 5MPa) and medium pressure boiler (pressure less than or equal to reach 3.9Mpa at 3 days), used in the manufacture of low and medium pressure boiler superheated steam tube, boiling water pipe, water wall tube, smoke tube and pipe arch bricks and so on, the general use of 10, 20, hot or cold rolled quality carbon structural steel. Usually need to pressure, curling, flaring, squash and other tests to ensure product quality and performance. Normally the container and steam pipelines with the operating pressure are not higher than 5.88Mpa operating temperature below 450C.

Chemical Composition (%):

Standard

Steel Code

Chemical Composition (%)

GB3087

10

0.070.13

0.170.37

0.380.6

≤0.030

≤0.030

0.30.65

20

0.170.23

0.170.37

0.380.6

≤0.030

≤0.030

0.30.65

 Mechanical Properities:

Standard

Steel Code

Tensile Strength(MPa)

Yield Strength(MPa)

Elongation(%)

GB3087

10

335475

≥195

≥24

20

410-550

≥245

≥20

The low and medium pressure boiler tubes are made of steel ingots or solid tube blanks, and then made by hot rolling, cold rolling or cold drawing.

High pressure boiler tube

The high pressure boiler tube is a type of boiler tube and belongs to the category of seamless steel tubes. High pressure boiler tubes are often used in high temperature and high pressure conditions.
High-pressure boiler tubes are mainly used to manufacture superheater tubes, reheater tubes, air guiding tubes, main steam tubes, etc. for high-pressure and ultra-high pressure boilers.
Due to the long-term operation of the boiler tube under high temperature and high pressure conditions, the material will creep, plasticity and toughness will decrease, the original structure will change, and corrosion will occur. Steel pipes used as boilers shall have:

  1. Adequate strength;
  2. Sufficient plastic deformation ability;
  3. Minimal aging tendency and hot brittleness;
  4. High resistance to oxidation, coal ash, natural gas corrosion, steam and stress corrosion at high temperatures;

Good structural stability and good process performance. The steel grades of high-pressure boiler tubes are carbon steel and pearlitic, ferritic and austenitic stainless steel. In order to improve the thermal efficiency and reduce fuel consumption of thermal power generating units, countries around the world are mainly developing large-capacity, high-parameter (high-temperature, high-voltage) thermal power units (1000MW or more). The steam pressure is increased to 31.5~34.3MPa, and the superheated steam temperature is 595-650°C, which develops to the ultra-high pressure critical pressure, which puts higher requirements on the high-pressure boiler tube. New steel grades have been developed for this purpose to meet the needs of high-parameter power station boilers.

High Pressure Boiler Tube:

Standard

 Grade

Chemical Composition (%)

Mechenical Properties

 C

 Si

 Mn

 P

 S

 Cr

 No

 V

 (Mpa)TS

 (Mpa)YS

 (%)E






DIN17175

 GB5310

20G

0.17-

0.24

0.17-

0.37

0.35-

0.65

0.03

0.03

/

/

/

410-550

≥245

≥24

 20

MoG

0.17-

0.24

0.17-

0.38

0.70-

1.00

0.03

0.03

/

/

/

≥415

≥240

≥22

15

MoG

0.12-

0.20

0.17-

0.37

0.40-

0.80

0.03

0.03

/

0.25-

0.35

/

450-600

≥270

≥22

15Cr1

MoG

0.12-

0.18

0.17-

0.37

0.40-

0.70

0.03

0.03

0.80-

1.10

0.40-

0.55

/

440-640

≥235

≥21

12Cr2

MoG

0.08-

0.15

≤0.50

0.40-

0.70

0.03

0.03

2.00-

2.50

0.90-

1.20

/

450-600

≥280

≥20

12Cr1

MoVG

0.08-

0.15

0.17-

0.35

0.40-

0.70

0.03

0.03

0.90-

1.20

0.25-

0.35

0.15-

0.3

470-640

≥255

≥21

Uses of boiler tubes

  1. Steam Boilers
  2. Power Generation
  3. Fossil Fuel Plants
  4. Electric Power Plants
  5. Industrial Processing Plants
  6. Cogeneration Facilities
  7. Waste HeatBoiler Tube in the following Spec/Grades

Standard of boiler tube: 

  • American society of mechanical engineers: ASME SA-106, ASME SA-192M, ASME SA-209M, ASME SA-210M, ASME SA-213M, ASME SA-335M, ASME SA-179M
  • American Society for Testing and Materials: ASTM A 106M, ASTM A 192M, ASTM A 210M, ASTM A 213M, ASTM A 335M, ASTM A 179M
  • European Standards: EN 10216-2
  • Deutsches Institut fǖr Normung: DIN 17175
  • Japaneses industrial standards: JIS G 3456JIS G 3461JIS G 3462

 Standard               

Grade

DIN 17175

St35.8, St45.8, 15Mo3, 13CrMo44, 10CrMo910, 14MoV63, 12Cr1MoV

ASTM A106M

ASME SA-106

A106 B

SA-106C

ASTM A192M

ASME SA-192M

A192

SA-192

ASTM A179

ASME SA 179

A179

SA 179

ASTM A209M 

ASME SA-209M

A 209T1, A209T1b, A 209T1a

SA-209T1, SA-209TIb, SA-209T1a

ASTM A 210M

ASME SA-210M

A 210A1 , A 210C

SA-210A1, SA-210C

ASTM A 213M

ASME SA-213M

A 213 T2,  A213 T11,  A213 T12,  A213 T22,  A213 T23, SA-213 T2, SA213-T11, SA213-T12, SA213-T22, SA213-T23

A 213 T24,  A213 T91,  A213 T911,  A213 T92,  A213 T122, SA-213 T24, SA213-T11, SA213-T911, SA213-T92, SA213-T122

TP304H,  TP321H,  TP347H,  S30432, TP310HCbN

EN 10216-2

P195GH, P235GH, P265GH, 16Mo3, 10CrMo5-5, 13CrMo4-5, 10CrMo9-10, X10CrMoVNb9-1

JIS G 3461

STB 340 , STB410, STB510

JIS G 3462

STBA 12, STBA13, STBA 20C, STBA22,STBA23, STBA24, STBA26

JIS G 3463

SUS304HTB , SUS321HTB

Note: Grades other than the a.m.chart can be made available through consultations.

Available Dimension Range:

Cold Finished Seamless Tube and Pipe:Φ8-114.3×1~20mm

Hot-rolled Steel Tube and Pipe:Φ114.3~720×5~120mm

Steel Grade

Standard

Applications

ASME(U.S.A)

DIN/EN(Euro)

Carbon steel

SA-106B, SA-192, SA-179, 
SA-210A1, SA-106C, SA-210C

P265GH, P195GH, P235GH

St35.8,St45.8

Economizer tube, 
Water wall tube

Mo Steel

SA-2209T1, SA-209T1a, SA-209T1b

15Mo3, 16Mo3

Water wall tube, 
Superheater tube, 
Reheater tube

Cr-Mo Steel

SA-213 T11, SA-213 T22 SA-213 T24, SA-213 T91

12Cr1MoV, 14MoV63

10CrMo910, X10CrMoVNb91

10CrMo5-5, 13CrMo4-5

Superheater tube,
 Reheater tube

Cr-Mo-W Steel

SA-213 T23, SA-214 T911, 
SA-213 T92, SA-213 T122

Superheater tube, 
Reheater tube

Austenitic Stainless steel

TP304, TP304H, TP321, TP321H, 

TP347, TP347H,TP316,TP316H,S30432, 
TP310HCbN

Superheater tube,
 Reheater tube

GB5310 20G boiler steel pipe

GB5310 20G boiler steel pipe - How to choose boiler tubes

GB 5310- 2008 standard is applicable to seamless tubes for making steam boiler whose pressure is high or higher and seamless tubes used as pipelines.

Grade 20G Seamless Steel Boiler Pipe is applicable to seamless tubes for making steam boiler whose pressure is high or higher and seamless tubes used as pipelines.

20G seamless steel pipe is a high-quality carbon structural steel, boiler material, the carbon content of 0.17-0.24%, tensile strength of 410Mpa, yield point 230-250Mpa. Is our main production of steel, we can provide 20G Seamless pipe with high quality and competitive price. Here to introduce you to our 20G seamless pipe basic chemical properties and mechanical properties.

Chemical Compositions(%) of GB5310 20G

Chemical elements Data
Carbon 0.17-0.24
Silicon 0.17-0.37
Manganese 0.70-1.00
Phosphorus(max) 0.03
Sulfur(max) 0.03
Chromium(max) 0.25
Molybdenum(max) 0.15
Cuprum(max) 0.2
Nickel(max) 0.25
Vanadium(max) 0.08

Mechanical Properties of GB5310 20G:

Properties Data
Yield Strength (Mpa) ≥415
Tensile Strength (Mpa) 240
Elongation (%) 22

The W.T. tolerance of GB5310 20G:

W.T.(S) Tolerance of W.T.
<3.5  +15%(+0.48mm min)
 -10%(+0.32mm min)
3.5-20 +15%,-10%
>20 D<219 ±10%
D≥219 +12.5%,-10%

Additional Condition

UT(Ultrasonic examination), AR(As Hot Rolled only), TMCP(Thermal Mechanical Control Processing), N(Normalized), Q+T(Quenched and Tempered),Z Direction Test(Z15,Z25,Z35), Charpy V-Notch Impact Test, The Third Party Test (such as SGS Test), Coated or Shot Blasting and Painting.

GB5310 20G boiler steel pipe Application

GB5310 20G seamless steel pipes are mainly used for pressure vessels, machinery, pipe fittings, oil and chemical industry.

GB5310 20G boiler steel pipe Other Name

GB5310 20G boiler steel pipe, 20G boiler steel pipe, 20G boiler pipe

ASTM A192 / A192M Standard Specification for Seamless Carbon Steel Boiler Tubes for High-Pressure Service

The ASTM A192 belongs to the carbon seamless tubes, which is specially designed for high, middle, low pressure purpose in seamless carbon steel boilers and as super heater tubes.

astm a192 tube - How to choose boiler tubes
Mark on the tubes

Material Comparison Tables (ASTM ℃KS, JIS, DIN, BS, NBN, NF, UNI)

Features Specifications

OD(mm) Wall Thickness Unit(mm)
2 2.5 3 3.5 4 4.5 5 6 6.5-7 7.5-8 8.5-9 9.5-10 11 12
Φ25-Φ28
Φ32
Φ34-Φ36
Φ38
Φ40
Φ42
Φ45
Φ48-Φ60
Φ63.5
Φ68-Φ73
Φ76
Φ80
Φ83
Φ89
Φ95
Φ102
Φ108
Φ114
Φ121
Φ127
Φ133
Φ140
Φ146
Φ152
Φ159
Φ168
ASTM
STANDARD
UNS NO.
KOREA/JAPANES

GERMAN

BRITISH
BELGIAN
FRENCH
ITALIAN
KS/JIS Symbol
KS/JIS Numbe
Re
marks
DIN Type

DIN

Number

Materiral

Number

Re
marks

B.S

Number

B.S Grade
Remarks
NBN Type
NBN Grade
Re
marks
AFNOR Type
NF Number
Re
marks
UNI Type
UNI Number
Re
marks

A 192

Seamless C-Steel Boiler Tube for High Pressure Service

K01201 STBH 340 / STB 340 D3563 / G3461 (30) St 35.8 17175 1.0305 3059 320 (27)(30) D45 837 (27) TU 37C A49-213 (27) C14 5462

(27)

ASTMA 192M / ASME SA-192M Chemical Compositions(%)

C Si Mn P S Cr Mo Cu Ni V
0.06-0.18 ≤0.25 0.27-0.63 ≤0.035 ≤0.035 / / / / /

ASTM A 192M / ASME SA-192M Mechanical Properties

Yield Strength (Mpa) Tensile Strength (Mpa) Elongation (%)
≥180 ≥325 ≥35

JIS Number and Corrensponding Foreign Standards

JIS
ASTM
BS
DIN
NF
ISO

Index Number

Standard Number

Grade

Tupe

Standard Number

Grade

Tupe

Standard Number

Grade

Tupe

Standard Number

Grade

Tupe

Standard Number

Grade

Tupe

Standard Number

Grade

Tupe

G3461
STB340
C
A161
LC
C
3059
HFS320
C
A49-245
TS34e
C
C010
(STB35)
A192
C
CFS320
C
TS34c
C
A226
C
ERW320
C
A556
GrA2
C
CEW320
C
A557
GrA2
C
S1 360
C
S2 360
C
ERW 360
C
CEW360
C
3606
ERW320
C
CEW320
C
CFS320
C
STB410
C
A179
GrC
C
3059
S1 440
C
17175
St45.8
C
A49-213
TU42c
C
2604/2
TS9H
C
(STB42)
A210
GrA1
C
S2 440
C
17177
St42.8
C
A49-215
TU42c
C
TW9H
C
A556
GrB2
C
ERW 440
C
A49-243
TS42c
A557
GrB2
C
CEW 440
C
A49-245
TS42c
3602
HFS 410
C
TS42c
CFS 410
C
ERW 410
C
CEW 410
C
3606
ERW 440
C
CEW 440
C
CFS 440
C
STB510
C
C
17175
19Mn5
C
A49-213
TU52C
C
2604/2
TS18
C
(STB52)
C
A49-248
TU52C
C

Scope:

1. This specification covers minimum-wall-thickness, seamless carbon steel boiler and superheater tubes for high-pressure service. 
2. The tubing sizes and thicknesses usually furnished to this specification are 1/2 in. to 7 in. [12.7 to 177.8 mm] outside diameter and 0.085 to 1.00 in. [2.2 to 25.4 mm], inclusive, in minimum wall thickness. Tubing having other dimensions may be furnished, provided such tubes comply with all other requirements of this specification.
3. Mechanical property requirements do not apply to tubing smaller than 1/8 in [3.2 mm] inside dimeter or 0.015 in. [0.4 mm] thickness.
4 When these products are to be used in applications conforming to ISO Recommendations for Boiler Construction, the requirements of specification A 520 shall supplement and supersede the requirements of this specification.
5. The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order.

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.

Manufacturing Process of Boiler Tube

20150625042048784878 - How to choose boiler tubes

The production method of the boiler tube is roughly divided into a cross-rolling method (Mengnesmann method) and an extrusion method. The cross-rolling method (Mennesmann method) first pierces the tube by a slanting roll and then extends it with a rolling mill. This method has a high production speed, but has high requirements on the processability of the tube blank, and is mainly suitable for the production of carbon steel and low-alloy boiler tubes.
The extrusion method is to pierce a tube blank or a steel ingot by a punching machine and then extrude it into a boiler tube by an extruder. This method is less efficient than the cross-rolling method and is suitable for producing a high-strength alloy boiler tube.
Both the cross-rolling method and the extrusion method must first heat the tube blank or the ingot, and the produced boiler tube is called a hot-rolled tube. Boiler tubes produced by hot working can sometimes be cold worked as needed. There are two methods for cold working: one is cold drawing, which is to draw the boiler tube through the extruding die to make the boiler tube become thinner and longer; the other method is cold rolling, which is to be Mengnesmann. The hot rolling mill invented by the brothers is applied to the method in cold working. The cold processing of the boiler tube can increase the dimensional accuracy and processing finish of the boiler tube and improve the mechanical properties of the material.

Quality problems of Boiler tubes

Boiler tube quality problems mainly in the cracks, shrinkage, peeling, pit, layered, pinhole, slag and so on. Boiler tube defects and injuries that may exist in the same smelting and rolling process.
The main defects in the surface of the boiler tube and an outer surface than the inner surface.
About 70 percent of these defects from the raw material (billets), billets in blowing insufficient residual slag material, shrinkage, etc., with which there may be rolled steel transverse cracks, laminated, folded, heavy leather and other defects, longitudinal cracks caused mostly rolling strain. If the boiler tube in the emergence of these defects or injuries, considers the material appeared discontinuous density within the material is damaged, it is possible leaks in the hydraulic pressure test, boiler pressure element is made at run time there may leak or burst pipes. Because of this, in order to ensure the quality of boiler pipe, whether it is related to a foreign country or boiler seamless steel pipe standards are clearly defined, as the process performance guarantee, steel hydraulic test should be made by the root.
The purpose of the hydrostatic test, there are two: one is the process of hydraulic test, its purpose is to test the material (or components) for leaks, that the sealing properties of materials; the other is the verification of the hydrostatic test, its purpose is to strength test material (or components) is adequate. From here, the hydrostatic test pressure boiler tube is part of the process of trial, is the material density test, if the test material is dense and continuous; it is not the strength of experimental verification.
Strength theory of mechanics of materials known from, seamless steel components are thin and long, and its diameter is very small, even for thin-walled tubules can withstand a lot of pressure.

Ways to Identify the Quality of SA 213 Boiler Tube      

It is important to know the quality of thing that you are going to purchase, here we are going to introduce some simple quality identification methods of SA 213 boiler tube.
First, low quality SA 213 boiler tube prone to fold. Folding is a variety of polylines formed by the surface of the SA 213 boiler tube, which often runs through the longitudinal direction of the entire product. The reason for the folding is due to the high efficiency of the poor manufacturers, the amount of pressure is too large, resulting in the ear, the next rolling to produce folding, folding products will crack after bending, SA 213 boiler tube strength decreased.
Second, poor quality SA 213 boiler tube surface prone to scarring.

There are two reasons:

  1. Poor SA 213 boiler tube material is not uniform, more impurities.
  2. Poor quality manufacturers guide guide equipment simple, easy to sticky steel, these impurities are easy to produce scar after the bite roll.

Third, poor quality SA 213 boiler tube without metallic luster, pale or similar pig iron color, there are two reasons:

  1. Its blank is adobe.
  2. The poor quality of the rolling material is not standard, their steel temperature is through the visual, so that can not be required according to the provisions of the austenite rolling, SA 213 boiler tube performance can not be achieved.

Fourth, low-quality boiler tube cross-section was oval, because the manufacturers in order to save the material, the first roll of the first roll is too large, the strength of this rebar greatly reduced, and does not meet the size of rebar The standard.
Five, low quality SA 213 boiler tube appearance is often numb phenomenon. The incontinence is due to the serious irregularity of the surface of the SA 213 boiler tube due to the wear of the groove. Due to poor quality SA 213 boiler tube manufacturers to pursue profits, often rolling rolling the most standard.

The derusting methods for high pressure boiler tube:

Cleaning: In order to achieve the removal of oil, grease, dirt, organic lubricant and similar organic matter, we can use the solvent, emulsion to clean the surface of high pressure boiler tube. But it can not remove the surface rust in high-pressure boiler tube, oxide, welding etc, so it only in anti-corrosion production only as an auxiliary means.
Removed rust by tools: Mainly use the wire brush and other tools for surface grinding of high pressure boiler tube, it can remove loose or tilt of the oxide, rust, welding slag and so on. Manual tool derusting can reach Sa2 level, power tools derusting can reach Sa3 level, and if the surface of the high pressure boiler tube attached to a solid iron oxide, tool rust effect is not so good, it will not achieve the requirements of anti-corrosion construction of the anchor depth.
Pickling: General use of chemical and electrolysis two methods to do pickling treatment, pipeline corrosion only use chemical pickling, and it can remove the scale, rust, the old coating, and sometimes can be used as a blasting after the re-treatment. Although the chemical cleaning surface can achieve a certain degree of cleanliness and roughness, but the anchor is shallow, and easy to cause pollution to the environment.
Rust removing by abrasive cleaning: The rust removing by abrasive cleaning is driven by high-power motor spray (throw) shot high-speed rotation of the blade, so that steel sand, steel balls, wire segments, minerals and other abrasive in the centrifugal force on the surface of the steel pipe spray (throw) shot treatment, it not only can completely remove rust, oxide and dirt, and also to achieve the required uniform roughness, which the high pressure boiler tube abrasive in the impact and the role of friction.

Internal Defect Control of Small-Diameter High-Pressure Boiler Tube

Defect localization and analysis, mainly for the defect depth 0.2 ~ 0.5mm, the length of 20 ~ 50mm superficial cracks, which causes the piercing of minute defects generated in the process, or rolling the first and second plurality of specifications by trauma, Four planes during rolling 20g high-pressure boiler tube by the inner surface of the oxide residue effects formed in the slide and scarring defects, these defects after rolling reduction of squash and stretch Zhang aggravated.
Through the high-pressure boiler tube double length number tracking found that injury concentrated in the steel tube end report first, twice-foot (from the pipe end within 25m), is closely related to the capillary head borax oxide accumulation, small-diameter steel pipe defect in the front of the capillary the higher the ratio of the rolling zone appears. Through the above analysis we can draw the following conclusions:

  • (1) the presence of perforated capillary end in addition to the adverse effects of oxidation issues that need to be improved.
  • (2) the presence of a work surface and rolling rack rolling defects within the designated road, we need to start to be addressed from the hole, lubrication improvement.
  • (3) Save dryer sheets high total reduction ratio in diameter, in the presence of the shortage of raw tube defects can not be completely eliminated during rolling.

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.
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.

Inspection and Test:

Chemical Composition Inspection, Mechanical Properties Test (Tensile Strength, Yield Strength, Elongation, Flaring, Flattening, Bending, Hardness, Impact Test), Surface and Dimension Test, No-destructive Test, Hydrostatic Test.

Surface treatment:

Oil-dip, Varnish, Passivation, Phosphating, Shot Blasting

What is boiler pickling

Boiler pipe often accumulate oxide or other contaminants in the process of manufacturing, transportation and installation, boiler heating surface corrosion damage in the initial running.
The the boiler has safely operated for a period of time, in the high heat load area (such as a burner zone) occurs oxide deposition of the pipe wall, resulting in over-temperature of the heating surface or tube rupture.
Natural water is an aqueous solution of electrolyte contact with the metal can easily generate electrochemical corrosion, salt scale deposition in the steam valve failure and valve leak may cause the valve action. , Boiler installed and ready to run in respect of a series of measures to ensure the cleaning of the heating surfaces.
Boiler pickling operations beginning, Condenser — feedwater system should be kept filled with demineralized water. And chemical cleaning pump equipment at full capacity flow corresponding to the establishment of recycling, including low-pressure heaters, deaerator, as well as high-pressure heaters, feed pumps should bypass. After the pickling cycle, and the fluid within the system reaches 200F, glycolic acid, formic acid and ammonium chloride inhibitors mixed solution was injected into the system. To ensure the uniformity of the concentration, the acid solution should be injected at a constant rate, i.e. the injection time equal to one complete cycle through the system needs time. Pickling is complete, it can be used in addition to the saline-filled system to discharge waste pickling solution and flush the system. Of condensate should pickling after filling containing 40ppm ammonia and 500ppm hydrazine to inactivate the system. Passivation during the operation, the pH value should be maintained at 9. O or greater, hydrazine concentration above 200ppm. Note that if some of the parts made of stainless steel of the feedwater heater, can not spend France formulated solution pickling.

With caustic period, there may have been suspended solids abrasion damage to the acid solution, or wash pumps and other equipment should be bypassed or remove the inner member. Valves and pipes should be checked to prevent acid accidental discharge, or equipment of accidental contamination. Should continue to cycle in the pickling solution, the first time after the return from the high-pressure heater 4-6 hours, once every half an hour in water samples sampling and analysis of the iron content. Feedwater heater bypass cleaning should change the fluid flow paths in the pickling period.

How to choose boiler tubes?

Tips for choosing good quality boiler tubes.

  1. As for good quality boiler tubes, its cross section should be smooth and even. If you see there is burr or uneven cross section, do not pick up these defective boiler tubes.
  2. You need to know the percent of impurities. Weight the pipes and measure its density. If it is low density, light boiler tubes will be poor quality.
  3. Check trademark. There will be standard trademark and words on seamless steel pipe from good quality boiler tubes manufacturers.
  4. Check the shape of boiler tubes. As for poor quality pipes, you will find oval shape on the side of it.
  5. Check the surface of boiler tubes. Bad rolling technology produce rough surface boiler tubes. Do not choose poor surface boiler tubes.

Source: China Boiler Tubes Manufacturer – Yaang Pipe Industry Co., Limited (www.metallicsteel.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@metallicsteel.com

Please notice that you might be interested in the other technical articles we’ve published:

Reference:

  • https://www.steeljrv.com/how-to-get-high-quality-boiler-tubes.html
  • https://www.yaang.com

Related News

العربيةБългарски简体中文繁體中文DanskNederlandsEnglishFrançaisDeutschBahasa IndonesiaItaliano日本語한국어LatinPortuguêsРусскийEspañolதமிழ்ไทยTürkçe