Welding process of a composite plate centrifugal compressor casing

Abstract

The present application relates to a kind of welding process of composite plate centrifugal compressor casing, for solving the technical problem of welding joint strength and corrosion resistance.The present application includes the following steps: step 1, each component is pretreated;Step 2, the surfacing treatment is carried out to upper and lower middle surface flange;Step 3, the upper support plate and the upper support ring are assembled and welded, to form upper support plate assembly;The lower support plate and the lower support ring are assembled and welded, to form lower support plate assembly;Step 4, the upper shell plate and the upper support plate assembly are assembled and welded together, while the lower shell plate and the lower support plate assembly are assembled and welded together;Step 5, the upper middle surface flange, the upper seal body, the upper shell plate and the upper side plate are welded together to form upper casing part;The lower middle surface flange, the lower seal body, the lower shell plate and the lower side plate are welded together to form lower casing part;Step 6, the upper casing part, the lower casing part and the wind drum are welded and assembled, to complete the welding of composite plate casing.

Description

TECHNICAL FIELD

[0001] The present application relates to a compressor casing, in particular to a welding process of a composite plate centrifugal compressor casing. BACKGROUND

[0002] Centrifugal compressors are widely used in petrochemical industry, coal chemical industry, acid making and other fields, for example, the casing flow passage surface of compressors such as recycle gas compressor and nitric oxide compressor working in corrosive conditions needs to have corrosion resistance. Such casing is usually processed by casting process using stainless steel material or by processing the whole through-flow surface of the casing with surfacing corrosion-resistant material, which has high manufacturing cost.

[0003] In order to reduce the manufacturing cost of the compressor, the casing is manufactured by welding the explosion composite plate made of Q345R and S30408, the low alloy steel plate made of Q345R and the 0Cr19Ni10 material. In order to ensure the successful welding of the casing, the technical problem of poor strength and corrosion resistance of the composite plate welding joint needs to be solved. SUMMARY

[0004] The present application provides a welding process of a composite plate centrifugal compressor casing to solve the technical problem of poor strength and corrosion resistance of the composite plate welding joint. The strength and corrosion resistance of the joint can be ensured by special welding joint form design, selection of matched gas shielded welding materials and corrosion-resistant surfacing manufacturing process.

[0005] To achieve the above purpose, the technical scheme of the present application is as follows:

[0006] A welding process of a composite plate centrifugal compressor casing, characterized by comprising the following steps:

[0007] Step 1, pretreating each part;

[0008] Step 2, surfacing the upper and lower middle surface flanges; after surfacing, stress relief treatment and middle surface processing are performed;

[0009] Step 3, assembling and welding the upper support plate and the upper support ring to form an upper support plate assembly; assembling and welding the lower support plate and the lower support ring to form a lower support plate assembly;

[0010] Step 4, assembling and welding the upper casing plate and the upper support plate assembly together, and assembling and welding the lower casing plate and the lower support plate assembly together;

[0011] Step 5, welding the upper middle surface flange, the upper sealing body, the upper casing plate and the upper side plate together to form an upper casing part;

[0012] Welding the lower middle flange, the lower sealing body, the lower shell plate and the lower side plate together to form the lower casing part;

[0013] Before assembling the upper shell plate with the upper side plate and the lower shell plate with the lower side plate, a processing step is needed to remove the clad metal on the upper end of the upper side plate and the lower end of the lower side plate, and the width H of the processing step is (1.5-2)T, T being the thickness of the upper shell plate;

[0014] The processing step enables the base layer of the upper shell plate and the upper side plate and the base layer of the lower shell plate and the lower side plate to be welded, and the clad layer of the upper shell plate and the upper side plate and the clad layer of the lower shell plate and the lower side plate to be welded;

[0015] Step 6: welding and assembling the upper casing part, the lower casing part and the air duct to complete the welding and assembly.

[0016] Further, in step 4, before assembling and welding the upper support plate with the upper shell plate and the lower support plate with the lower shell plate, a ring groove is arranged on the inner wall of the upper shell plate and the lower shell plate at the corresponding welding position, so that one side of the upper support plate and the lower support plate is located in the ring groove.

[0017] A K-shaped groove is arranged at the welding position of the upper support plate and the lower support plate, so that the base layer of the upper support plate and the upper shell plate and the base layer of the lower support plate and the lower shell plate are welded, and the clad layer of the upper support plate and the upper shell plate and the clad layer of the lower support plate and the lower shell plate are welded.

[0018] Further, when welding the upper support plate with the upper shell plate and the lower support plate with the lower shell plate, the step width of the processing step is 10 cm, and the step angle α is 120-150°; the groove angle γ of the K-shaped groove is 30-45°.

[0019] Further, step 2 is specifically as follows: first, processing the surface to be surfacing of the upper middle flange and the lower middle flange, so that the upper middle flange and the lower middle flange are thinned by the thickness required for surfacing, and then performing surfacing treatment on the upper middle flange and the lower middle flange, so that the upper middle flange and the lower middle flange after surfacing treatment reach the thickness when not thinned.

[0020] Further, when welding the base layer with the base layer, the welding is performed by using the shielded metal arc welding process, wherein the welding wire is H08Mn2SiA, the diameter of the welding wire is φ1.6 mm, and the protective gas is a mixed gas composed of 80% Ar and 20% CO2.

[0021] Further, when welding the clad layer with the clad layer, the welding is performed by using the flux-cored wire gas shielded welding, the welding wire is E308LT1, the diameter of the welding wire is 1.6 mm, and the protective gas is 99.98% CO2.

[0022] Furthermore, when welding the composite plate to the S30408 ​​part, a gas metal arc welding process is adopted, the welding wire grade is E309LT1-1, the diameter of the welding wire is φ1.6mm, and the shielding gas is a mixture of 98%Ar and 2%O2.

[0023] Furthermore, when welding the transition layers together, flux-cored wire gas shielded welding is used. The wire grade is E309LT1, the wire diameter is φ1.6mm, and the shielding gas is 99.98% CO2.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention solves the technical challenge of ensuring joint strength in composite plates by designing two special joint forms: a K-shaped bevel and a machined step. Using gas metal arc welding (GMAW) to weld the composite plates not only guarantees the strength of the welded joint but also satisfies the corrosion resistance requirements of the cladding metal. Compared to manual arc welding, it offers higher welding efficiency and produces aesthetically pleasing weld formations. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the housing to be welded in this invention;

[0027] Figure 2 for Figure 1 Enlarged view of point I in the middle;

[0028] Figure 3 for Figure 1 Enlarged schematic diagram of section II.

[0029] The reference numerals in the attached figures are as follows:

[0030] 1. Upper shell plate, 2. Upper side plate, 3. Upper center split flange, 4. Upper sealing body, 5. Upper support ring, 6. Upper support plate, 7. Lower shell plate, 8. Lower side plate, 9. Lower center split flange, 10. Lower sealing body, 11. Lower support ring, 12. Lower support plate, 13. Air duct, 14. Base layer, 15. Multilayer. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0032] A welding process for a composite plate centrifugal compressor housing, used for welding such as Figure 1 The centrifugal compressor casing shown is designed to ensure that the strength of the welded joint and the corrosion resistance of the weld meet the requirements. The implementation steps are as follows:

[0033] The upper shell plate 1, lower shell plate 7, upper side plate 2, lower side plate 8, upper support plate 6 and lower support plate 12 of the casing are all made of Q345R+S30408 ​​explosion-proof composite plate, that is, the base layer is Q345R material, the cladding layer is S30408 ​​material, and a transition layer is set between the base layer and the cladding layer.

[0034] The upper sealing body 4, the lower sealing body 10, the upper support ring 5, and the lower support ring 11 are all made of S30408 ​​material.

[0035] Because the parts are made of different materials, welding must be performed between parts made of the same material.

[0036] Before welding, it is necessary to clean the oil and corrosion from the surfaces of all parts and the welding area.

[0037] Step 1: After depositing a corrosion-resistant layer on the surfaces of the upper center-split flange 3 and the lower center-split flange 9, assemble them with other parts. Both the upper center-split flange 3 and the lower center-split flange 9 are made of Q345R material.

[0038] Step 2: Welding of components

[0039] The upper support plate 6 and the upper support ring 5 are welded together to form the upper support plate assembly. Since the outer circle of the upper support plate 6 will contact the inner surface of the upper shell plate 1, direct welding between the two would lead to unstable welding. Therefore, it is necessary to process the upper support plate 6 as follows: Figure 2 The K-shaped welding bevel is shown.

[0040] The lower support plate 12 and the lower support ring 11 are assembled and welded to form a lower support plate assembly. Then, a K-shaped welding bevel is processed on the lower support plate 12 to allow welding between the same materials.

[0041] Step 3: The upper center flange 3, upper sealing body 4, upper shell plate 1, and upper side plate 2 are welded together to form the upper housing component.

[0042] The lower center flange 9, lower sealing body 10, lower shell plate 7, and lower side plate 8 are welded together to form the lower housing component.

[0043] Step 4: Weld the upper housing support assembly to the upper housing assembly from Step 3. After the weld is inspected and found to be qualified, perform heat treatment to relieve stress.

[0044] Step 5: Weld the lower housing components, lower support plate assembly, air duct and other parts. After the welds pass inspection, perform stress-relieving heat treatment.

[0045] In step 1: Before welding, the surfaces of the upper and lower split flanges 3 and 9 are machined to reduce the required weld thickness. Then, welding is performed on the upper and lower split flanges 3 and 9, ensuring that their final thickness is the same as before the weld reduction. This welding process provides corrosion protection for the upper and lower split flanges 3 and 9. The thickness of the weld overlay is not less than the designed cladding thickness δ + 10 mm.

[0046] When welding the upper support plate 6 and the upper shell plate 1, an annular groove shall be machined on the inner surface of the upper shell plate 1 to remove the cladding metal. The width of the annular groove shall be the thickness of the support plate K + (10~20) mm, and the chamfer β of the annular groove shall be 120~150°. When welding the upper support plate 6 and the upper shell plate 1, the base layer, transition layer and cladding layer shall be welded according to the corresponding processes.

[0047] Figure 2 As shown, a K-shaped bevel is machined at the connection point between the upper support plate 6 and the upper shell plate 1, with a bevel angle γ = 30-45°. A step is also machined at the interface between the base layer and the cladding layer of the upper support plate 6 and the lower support plate 12, with a step width of 10mm and a step angle α = 120~150°, to facilitate welding of the base layer between the upper support plate 6 and the upper shell plate 1. This avoids heat concentration at the base layer and cladding layer sections during welding of the base metal, preventing delamination of the cladding layer metal, and also prevents contamination of the cladding layer metal during base metal welding.

[0048] The welding method of the lower support plate 12 and the lower shell plate 7 is the same as that of the upper shell plate 1 and the upper support plate 6. Both require the machining of annular grooves and K-shaped bevels at the corresponding positions.

[0049] Before assembling the upper shell 1 and upper side plate 2, and the lower shell 7 and lower side plate 8, as follows: Figure 3 As shown, a step needs to be manufactured first to remove the cladding metal from the upper end of the upper side plate 2 and the lower end of the lower side plate 8. The width of the step is H = (1.5~2)T, where T is the thickness of the upper shell plate 1, and the step angle α = 120~150°. The base layer is welded to the base layer in sequence, then the transition layer is welded to the transition layer, and finally the cladding layer is welded to the cladding layer. The upper shell plate 1 and the lower shell plate 7 have the same thickness.

[0050] When welding composite plates, different welding materials are used for the base layer, transition layer, and cladding layer metals. The base layer is welded using gas metal arc welding (MAG), with wire grade H08Mn2SiA, wire diameter φ1.6mm, and shielding gas 80% Ar + 20% CO2. Welding between transition layers uses flux-cored wire gas shielded welding, with wire grade E309LT1, wire diameter φ1.6mm, gas flow rate 20-25L / min, wire extension 15-25mm, welding current 150-280A, and shielding gas 99.98% CO2. Welding between cladding layers also uses flux-cored wire gas shielded welding, with wire grade E308LT1, wire diameter φ1.6mm, gas flow rate 20-25L / min, wire extension 15-25mm, welding current 150-280A, and shielding gas 99.98% CO2.

[0051] The composite plate is welded to S30408 ​​material using gas metal arc welding (FCAW) process. The welding wire grade is E309LT1-1, the welding wire diameter is φ1.6mm, and the shielding gas is 98%Ar+2%O2.

[0052] The center-part surfaces of the casing (including the center-part flange) are surfacing. The process is as follows: Welding between transition layers uses flux-cored wire gas shielded welding (FAW). Wire grade: E309LT1, wire diameter: φ1.6mm, gas flow rate: 20-25L / min, wire extension: 15-25mm, welding current: 150-280A, shielding gas: 99.98% CO2. Welding between cladding layers uses flux-cored wire gas shielded welding (FAW). Wire grade: E308LT1, wire diameter: φ1.6mm, gas flow rate: 20-25L / min, wire extension: 15-25mm, welding current: 150-280A, shielding gas: 99.98% CO2, wire composition: C≤0.04, Mn0.5-2.5. Si≤1.0, Cr18.0-21.0, Ni9.0-11.0, Mo≤0.5, CU≤0.5, P≤0.04, S≤0.03.

[0053] The welding process in question involves the following steps:

[0054] (1) When welding the composite plate, as shown in the enlarged figure II, first weld the base metal. The preheating temperature within 200mm on both sides of the welding bevel of the casing is 10~150℃. The interlayer temperature is controlled at 300-400℃, and the welding heat input is controlled within 30KJ / cm. After the base metal is welded, the transition layer and the cladding layer are welded. The interlayer temperature is controlled within 150℃, and the heat input is controlled within 15 KJ / cm. The thickness of the transition layer is controlled within 2-3mm.

[0055] (2) When welding the composite plate to stainless steel S30408 ​​parts, the interpass temperature should be controlled within 150℃ and the line energy should be controlled within 15 KJ / cm. When welding to a distance of not less than 8mm from the surface of the part, an isolation layer should be deposited on the surface of Q345 material inside the bevel. After grinding, fill and cover welding should be performed to ensure that the chemical composition of the surface in contact with the medium is uniform.

[0056] (3) When welding the split surface, the welding process parameters are the same as those of the composite plate.

Claims

1. A welding process for a composite plate centrifugal compressor housing, characterized in that, Includes the following steps: Step 1: Pre-process each component; Step 2: Perform overlay welding on the upper center-split flange (3) and the lower center-split flange (9); after the overlay welding is completed, perform stress relief treatment and process the center-split surface; Step 3: Assemble and weld the upper support plate (6) and the upper support ring (5) to form the upper support plate assembly; assemble and weld the lower support plate (12) and the lower support ring (11) to form the lower support plate assembly; Step 4: Assemble and weld the upper shell plate (1) and the upper support plate assembly together, and simultaneously assemble and weld the lower shell plate (7) and the lower support plate assembly together. Before the upper support plate (6) and the upper shell plate (1) and the lower support plate (12) and the lower shell plate (7) are assembled and welded, annular grooves are set at the corresponding welding positions on the inner walls of the upper shell plate (1) and the lower shell plate (7) so that one side of the upper support plate (6) and the lower support plate (12) is located in the annular groove. Step 5: Weld the upper center flange (3), upper sealing body (4), upper shell plate (1) and upper side plate (2) together to form the upper housing component; The lower center split flange (9), lower sealing body (10), lower shell plate (7) and lower side plate (8) are welded together to form the lower housing component; Before assembling the upper shell plate (1) and the upper side plate (2) and the lower shell plate (7) and the lower side plate (8), it is necessary to manufacture and process steps to remove the cladding metal at the upper end of the upper side plate (2) and the lower end of the lower side plate (8). The width of the processing step H = (1.5~2)T, where T is the thickness of the upper shell plate (1). The upper shell plate (1), lower shell plate (7), upper side plate (2), lower side plate (8), upper support plate (6) and lower support plate (12) are all made of Q345R+S30408 ​​explosion composite plate, and a transition layer is provided between the base layer and the cladding layer; By processing steps, the base layer between the upper shell plate (1) and the upper side plate (2) and the lower shell plate (7) and the lower side plate (8) are welded together, the transition layer is welded together, and the cladding layer is welded together. When welding the base layer to the base layer, the gas metal arc welding process is used. The welding wire is of grade H08Mn2SiA with a diameter of φ1.6mm. The shielding gas is a mixture of 80% Ar and 20% CO2. When welding the layers together, flux-cored wire gas shielded welding is used. The wire grade is E308LT1, the wire diameter is 1.6mm, and the shielding gas is 99.98% CO2. When welding the transition layers together, flux-cored wire gas shielded welding is used. The wire grade is E309LT1, the wire diameter is φ1.6mm, and the shielding gas is 99.98% CO2. Step 6: Weld and assemble the upper housing component, lower housing component, and air duct to complete the welding assembly.

2. The welding process for a composite plate centrifugal compressor housing according to claim 1, characterized in that, In step 4, K-shaped bevels are provided at the welding positions of the upper support plate (6) and the lower support plate (12) so that welding can be achieved between the upper support plate (6) and the upper shell plate (1) and between the lower support plate (12) and the lower shell plate (7), between the base layer and the base layer, between the transition layer and the transition layer, and between the cladding layer and the cladding layer.

3. The welding process for a composite plate centrifugal compressor housing according to claim 2, characterized in that, When welding the upper support plate (6) to the upper shell plate (1) and the lower support plate (12) to the lower shell plate (7), the step width of the processing step is 10cm, the step angle α = 120~150°, and the bevel angle γ of the K-shaped bevel is 30~45°.

4. The welding process for a composite plate centrifugal compressor housing according to claim 2 or 3, characterized in that, Step 2 is as follows: First, process the surfaces of the upper center split flange (3) and the lower center split flange (9) to be welded, so that the upper center split flange (3) and the lower center split flange (9) are thinned to the required thickness for welding. Then, perform welding on the upper center split flange (3) and the lower center split flange (9) so that the upper center split flange (3) and the lower center split flange (9) after welding are as thick as they were before thinning.

5. The welding process for a composite plate centrifugal compressor housing according to claim 4, characterized in that: When welding the composite plate to the S30408 ​​part, the gas metal arc welding process is adopted. The welding wire grade is E309LT1-1, the diameter of the welding wire is φ1.6mm, and the shielding gas is a mixture of 98%Ar and 2%O2.

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