Hydraulic Cylinder Welding

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Hydraulic Cylinder Welding


Welding on hydraulic cylinder is the most critical part of good quality. Ningbo LD has very strictly processing steps on welding quality control. Except experienced welders, good welding machines are also the key of the good welding quality. Our welding machines controllers are importing from Japan on the brand of Panasonic, whose a Constant Penetration Control Function that allows for uniform penetration throughout the weld assures our weld integrity is superior.


Company’s welding processing details are according to AWS D1.1–Structural Welding Code-Steel standard, and all welders are approved by AWS D1.1 license accordance with WPQ-Welder Performance Qualification. Company has AWS WI inspectors on welding quality inspecting. Every new prototype of welding part, required for WPS-Welding Procedure Specification and PQR-Procedure Qualification Report.


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WPS-Welding Procedure Specification


Company always keep the way that send new prototype welding parts to professional third agent for welding quality checking. Our WPS-Welding Procedure Specification is on the basis of AWS D1.1-Structural Welding Code-Steel standard. Once the welding parts qualified, our main production processing procedure will strictly follow the approved specification.


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PQR-Procedure Qualification Report



VT-Visual Testing

After welding, required visual testing one by one on welding area. Assurance that the welding is doing according to drawing requirements, removing welding slags before cleaning.

PT-Liquid Penetrant Testing

Penetration test is to detect whether there are defects on the surface of weld fusion surface, to avoid problems such as crack, non-fusion, non-penetration, porosity, etc.
Ningbo LD’s cylinders whose parts related to welding , need to be qualified for the following penetration test.

Joint groove welding’s penetration testing between tube and oil port
Joint groove welding’s penetration testing between tube and base end part
T-Joint groove welding’s penetration testing between rod and rod part
T-Joint groove welding’s penetration testing between base end part and earring part.

MT-Magnetic Particle Testing

Fluorescent magnetic particle detection is the way to test the welding surface and near-surface defects, such as cracks, arc pit cracks, interlayer non-fusion, etc.
Ningbo LD’s cylinders whose parts related to welding , need to be qualified for the following Fluorescent magnetic particle test.

Joint groove welding’s penetration testing between tube and oil port
Joint groove welding’s penetration testing between tube and base end part
T-Joint groove welding’s penetration testing between rod and rod part
T-Joint groove welding’s penetration testing between base end part and earring part.

RT-Radiographic Testing

Radiographic is the way to test the welding surface and near-surface defects, such as cracks, arc pit cracks, interlayer non-fusion, etc.
Ningbo LD’s cylinders whose parts related to welding , need to be qualified for the following Fluorescent magnetic particle test.

Radiographic inspection of girth welding area
Longitudinal radiographic inspection of welding area

Corrosion Metallographic Detection

Corrosion Metallographic Detection is used to test the penetration on the welding and near welding area’s quality. Macroscopic test was carried out reference to AWS D1.1/D1.1M:2015 Clause 4.9.4.

No crack on the weld / base metal
No lack of fusion between weld metal and base metal
No visible undercuts
No visible piping porosity

UT-Ultrasonic Testing

Ultrasonic testing is used to detect internal defects in welding seams (e.g. cracks, non-fusing, non-penetration, porosity, etc.).
Ningbo LD’s cylinders whose parts related to welding , need to be qualified for the following ultrasonic test.

Joint groove welding’s penetration testing between tube and oil port
Joint groove welding’s penetration testing between tube and base end part
T-Joint groove welding’s penetration testing between rod and rod part
T-Joint groove welding’s penetration testing between base end part and earring part.


Mechanical Property Testing

Mechanical property testing is used to test the welding article’s mechanical strength is strong enough or not. Mainly including Bend Test and Tensile Test.

Bend Test: Bend test was carried out reference to AWS D1.1/D1.1M:2015 Clause 4.9.3.1, bending angle is 180 °

Tensile Test: Tensile test was carried out reference to AWS D1.1/D1.1M:2015 Clause 4.9.3.4.