PRODUCT

product display

Industrial seamless pipe series

Tube series

Round steel series

Duplex Steel Series

Stainless steel pipe flange series

U-tube series

  • 700Million (RMB)±

    Annual output value

  • 100000㎡±

    Area

  • 30000Ton±

    Annual output of steel pipes

  • 350People±

    Total employees

Pengye Holding Group Co., Ltd.

Pengye Holding Group Co., Ltd. was established in 1992. It is located at No. 55, Yunyanshan Road, Xiping Street, Songyang County, Lishui City, Zhejiang Province. It covers an area of 100,000 square meters, with a registered capital of 100.08 million yuan, fixed assets of 120 million yuan, and an annual output of more than 30,000 tons of stainless steel pipes, with an annual output value of over 700 million yuan. The company has strong technology and complete facilities.

See More

QUALITY

Quality Management

Production Equipment

The main production equipment includes: chain cold drawing machine, cold rolling mill, radial bottom solid solution heat treatment furnace, straightening machine, press straightening machine, pickling supporting facilities

See More

Testing equipment

Equipped with advanced testing equipment such as universal material testing machine, eddy current flaw detector, ultrasonic flaw detector, water pressure testing machine, portable spectrometer and physical and chemical analysis

See More

Honors and Qualifications

Our company has established ISO9001 quality management system in 2006 and has been running effectively

See More

NEWS

Our company adheres to the quality policy of "manufacturing high-quality products,
pursuing excellence, continuous improvement and customer satisfaction" to provide domestic
customers with high-quality products and sincere and perfect after-sales service.

Weight calculation formula and description of stainless steel seamless pipe

There is a complete formula for calculating the weight of stainless steel seamless pipes, in which different materials correspond to different coefficients. You can save this article for future use.The weight calculation formula for stainless steel seamless pipes: Weight (kg) = (outer diameter-wall thickness × wall thickness × coefficient × length.In this formula, the outer diameter represents the outer diameter of the pipe, the wall thickness represents the thickness of the pipe wall, the length represents the total length of the pipe, and the coefficient is determined according to the stainless steel material.The coefficients of different materials are as follows:‌304: 0.02491‌316L: 0.02513Duplex steel: 0.02507310S: 0.02495Note that the units must be unified, the outer diameter/wall thickness is mm, and the length is m. Confusion will cause the result to deviate by a thousand times! Do not use the wrong coefficient, otherwise there will be deviations. Regarding the measurement of wall thickness, industrial pipes allow a wall thickness tolerance of ±10%, and high-precision requirements require actual measurement.

2025/06/05

What indicators are suitable for storage conditions of stainless steel seamless pipes?

The storage of seamless stainless steel pipes is particular. It not only requires environmental control, but also requires the selection of appropriate storage sites and methods, as well as good packaging management and risk prevention and control!The control of the environment for seamless stainless steel pipes lies in humidity, relative humidity, chloride ion concentration and ventilation requirements. Humidity control at -20℃～40℃ is ideal, because >60℃ will cause lubrication failure, <-10℃ will cause material embrittlement; relative humidity should be ≤60%, >70% will cause a surge in the risk of rust; chloride ion concentration needs to be <10ppm, and coastal areas should be monitored! >20ppm will induce pitting; air circulation should also be maintained, and a closed and windless environment will cause moisture accumulation.Seamless stainless steel pipes also have requirements for storage sites and storage methods: the storage site should choose a clean, dry and hardened ground, away from pollution sources such as chemical areas/garbage dumps. In the face of special scenarios such as coastal warehouses, anti-corrosion coatings and dehumidification systems should be installed. Only large pipes can be stored in the open air, but they must also be covered with rainproof cloth. Small and medium-sized pipes are stored in warehouses, with the pipes ≥10cm above the ground, and wooden pallets or rubber pads are used to isolate them from carbon steel materials!The new stainless steel seamless pipes should retain the original packaging film (valid for 6 months). If damaged, they should be replaced in time to avoid direct sunlight to accelerate aging. If the packaging is opened, it should be coated with anti-rust oil and wrapped with moisture-proof paper.After that, risk prevention and control measures should be taken:1. Regular spot checks (once a month) + humidity monitor alarm to eliminate the risk of surface rust (if found, neutral detergent should be used to wipe + passivation treatment).2. Rubber coating on the corners of the shelves + no more than 3 layers of stacking are allowed to avoid mechanical damage (scratched pipes should be isolated and repaired separately).3. It is forbidden to store them in the same warehouse with acids/alkalis/salts to prevent chemical pollution (pollutants should be isolated immediately + ventilated and diluted).In short, the storage of stainless steel seamless pipes should be kept clean and dry, isolated and anti-collision, and regularly monitored. None of the three can be missing.

2025/06/05

Causes and countermeasures of surface corrosion of stainless steel seamless pipes

Although stainless steel seamless pipes are called stainless steel, they are not rust-free. When corrosion occurs on the surface, the main reason is rust or stress corrosion cracking.Rust may occur because of the use of stainless steel seamless pipes in corrosive environments (chloride ions), or because of the acid corrosion caused by the adhesion of oil/organic juice (such as noodle soup, vegetable juice) on the surface of the steel pipe. The surface needs to be wiped with a neutral detergent regularly to avoid the accumulation of pollutants. Coastal areas or chemical environments need to be changed to more corrosion-resistant stainless steel materials (316L) to resist chloride ions.Another reason is stress corrosion cracking, which refers to spider web-like cracks on the inner wall of the pipe, especially under high temperature and high pressure. Stainless steel seamless pipes should be avoided from long-term contact with ammonia-containing and strong acid media. Solution treatment must be performed after welding (1050℃ rapid cooling to eliminate internal stress).

2025/06/05

Detailed introduction to the process flow of stainless steel seamless pipe

Stainless steel seamless pipes have to peel several layers from ingot to finished product.First, heat the 304 and 316L stainless steel ingots to more than 1200 degrees to soften them, and then use a tapered roller piercing machine to punch out a hollow rough tube.The hot-rolled pipe is directly rolled on a three-roller oblique rolling mill, and the wall thickness can be reduced to more than 2.5mm, which is suitable for large-diameter oil pipelines. If you want to make thin pipes for precision medical equipment, you have to cold draw. Use a mold to pull the pipe into a 6mm small pipe at room temperature, and anneal it repeatedly to eliminate stress, otherwise it will easily crack.The pickling process is more troublesome. Use hydrofluoric acid and nitric acid to gnaw off the oxide scale, and then use a high-pressure water gun to rinse it inside and out, otherwise the surface will be full of pitting. The cold-rolled pipe must also pass the metal flaw detector and ultrasonic bang bang scan to see if there are any hidden scratches. Only qualified ones can be polished to a mirror finish before leaving the factory. The most valuable material is 316L. With a little molybdenum, it can't even be corroded by seawater. The reactors in chemical plants are all made of this material.

2025/06/05

It turns out that stainless steel seamless pipes can be found everywhere!

Stainless steel seamless pipe is a seamless "steel straw" that can be seen everywhere from chemical plants to nuclear power plants.In chemical plants, stainless steel seamless pipe is the leader, which can transport deadly liquids such as sulfuric acid and caustic soda.In oil pipelines, stainless steel seamless pipe is standard, and it can transport oil and gas underground, and it is as stable as an old dog in a high-pressure environment.In hospitals, stainless steel seamless pipe is a "hidden model" that can be used as a sterile oxygen pipe in an operating room, and the surface is as smooth as a mirror.In food factories, stainless steel seamless pipes are frequent visitors. The pipes in beer fermentation tanks have to be dumped if they rust.In buildings, stainless steel seamless pipes are the new favorite. The air conditioning water pipes in high-end office buildings have not leaked for 40 years.The reason why they can be used in these places is that stainless steel seamless pipes contain chromium elements, which will form a protective film when they encounter corrosion. They are also tough and durable, not afraid of high pressure, and the inner wall is smooth and has no seams, so bacteria have no place to hide.

2025/06/05

How to detect the composition accuracy of stainless steel seamless pipes?

Stainless steel seamless pipe is a high-pressure and corrosion-resistant pipe with strong integrity and no welds, which is manufactured by hot rolling/cold drawing. In terms of its process, hot rolling includes heating, perforating, rolling, etc. of round tube billets, which is suitable for large-diameter pipes; while cold drawing improves accuracy through annealing and pickling, and the wall thickness tolerance can be controlled within ±0.1mm.Direct reading spectrometer is commonly used to detect the composition of stainless steel seamless pipes, analyzing elements such as Cr and Ni with an accuracy of ±0.005%. XRF is used for on-site rapid screening but cannot measure light elements, and carbon and sulfur require infrared absorption method assistance. Nuclear power plant pipes need to control boron ≤0.0015%, cobalt ≤0.05%, and food-grade pipes require that the dissolution of heavy metals such as lead and cadmium meet GB 4806.9 standards. The surface treatment uses electrolytic polishing to make the inner wall roughness Ra ≤0.4μm, and the outer wall is pickled and passivated to enhance corrosion resistance. The dimensional accuracy of the cold-rolled tube outer diameter is ±0.05mm, and the hot-rolled tube tolerance is ±1.5%. Uneven wall thickness may cause stress concentration.The application scope of stainless steel seamless pipes includes petrochemical, medical, nuclear power, etc. Nuclear power grade seamless pipes require ultrasonic and radiographic flaw detection, petrochemical seamless pipes require 25kg airtightness test, and medical seamless pipes require biocompatibility verification.

2025/06/05

What circumstances will cause the stainless steel seamless pipe to burst?

Stainless steel seamless pipes will not burst under normal circumstances. The main reasons for their bursting are related to materials, processes, welding, and use.If the chemical composition of the stainless steel seamless pipe material is deviated, such as insufficient nickel and chromium content or excessive carbon content, the toughness of the seamless pipe will decrease, the hardness will increase, and brittle cracks will easily occur under high pressure. The steel strip of the medium frequency furnace has many impurities and the carbon content exceeds the standard. The risk of fracture during bending processing is significant; in addition, there are abnormal internal structures, such as inclusions, pores or coarse grains that weaken the compressive strength, and cracks expand from weak points when under pressure.In terms of process, improper rolling of stainless steel seamless pipes, such as excessive rolling force to form microscopic large holes, or uneven wall thickness resulting in local pressure exceeding the limit; improper heat treatment, insufficient solution treatment, and residual internal stress will accelerate the cracking tendency during service.In terms of welding, the weld quality of stainless steel seamless pipes is poor, and defects such as incomplete penetration and undercuts form high-strength stress concentration points, and cracks spread along the welds; the welds are not completely passivated after welding, and the corrosive medium preferentially erodes the weld area, causing bursting. During the use of stainless steel seamless pipes, if the design pressure is exceeded for a long time or the pressure fluctuates frequently, metal fatigue cracking will occur. Chloride ion environment can also induce stress corrosion cracking. In addition, there is insufficient support during installation or thermal expansion and contraction are not compensated, resulting in additional mechanical stress superposition.

2025/06/05

How important is the skin condition of stainless steel seamless pipe?

The skin state of the stainless steel seamless pipe is the surface state, which is very important for it and directly affects its durability and usage scenarios.First of all, it has its own anti-fouling film. There is a layer of chromium oxide film (similar to the anti-scratch coating of mobile phones) on the surface of the stainless steel seamless pipe that is invisible to the naked eye. When it encounters chemicals such as acid, alkali, and salt, this film will self-repair to prevent the pipe from being corroded and rusted. When it is used in seawater treatment equipment, it depends on this film to withstand the attack of salt!In addition, it is as smooth as glass. The stainless steel seamless pipe is polished during production (for example, it is polished with sandpaper and then electrolytically polished). There is almost no bump on the surface, so that it is not easy for the liquid to flow through. This "silky" effect is particularly needed for surgical instruments in hospitals and beverage delivery pipes in food factories to avoid bacteria and dirt.Stainless steel seamless pipes will not peel at high temperatures. Even if they are subjected to high temperatures of more than 400°C in the boiler for a long time, the surface will not peel or oxidize and fall off. The steam pipes of thermal power plants rely on this feature to maintain stable transmission.Another point is that it is environmentally friendly and pollution-free. The manufacturing and use process of stainless steel seamless pipes does not release toxic substances. Even the chemicals used for polishing are environmentally friendly formulas. There is no need to worry about pollution when filling drinking water or making medicines.Stainless steel seamless pipes are like wearing protective suits from the inside to the outside. They are not only corrosion-resistant and high-temperature-resistant, but also environmentally friendly and non-sticky. Therefore, they can be seen from the reactors in chemical plants to the water purifiers at home.

2025/06/05

Why do stainless steel seamless pipes have internal cuts?

The inner straight pipe in the production of stainless steel seamless pipe is a common defect of the automatic pipe rolling mill and a difficult problem to solve. In most cases, the straight path is small and will not turn the stainless steel seamless pipe into waste; but sometimes, when rolling aviation pipes and alloy stainless steel seamless pipes, this defect will cause great damage, so it should be paid attention to.The reason for the inner straight line defect in the production of stainless steel seamless pipes is that there are concave and convex defects on the surface of the rolling pipe plug, such as the burning of the oxide scale welded on the plug, the wear of the plug, the deformation of the plug shape, etc., which scratches the inner and outer surfaces of the stainless steel seamless pipe. Due to the characteristics of longitudinal rolling, the scratches are linear, so they are called inner straight paths.The inner cut of stainless steel seamless pipes is caused by unreasonable plug design, sharp protrusions on the edge of the connecting rod connecting the plug, or metal spot welding scratching the inner and outer surfaces of the capillary. The design of the plug is unreasonable. If the fillet of the inverted cone is too small and the edge is sharp, the inner and outer surfaces of the capillary will be scratched. If the cone angle of the expansion section of the used plug is inconsistent with the cone angle of the roller outlet, the plug is of poor quality or there are defects on the plug surface, the inner and outer surfaces will also be scratched.

2025/06/05

What are the product characteristics of stainless steel seamless pipes?

Stainless steel seamless pipe is a long steel strip with a hollow cross-section and no seams around it. The thicker the wall thickness of the product, the more economical and practical it is. The thinner the wall thickness, the higher its processing cost will be. So do you know what are the product characteristics of stainless steel seamless pipe?The product characteristics of stainless steel seamless pipe are as follows:1. Chemical analysis: Chemical analysis of the chemical composition of the material, the chemical composition meets the standard requirements.2. Air pressure and water pressure test: The pressure-resistant pipes are subjected to water pressure test one by one. The specified pressure value is not maintained for no less than 5 seconds and there is no leakage. The conventional supply water pressure test is 2.45MPa. The air pressure test is P=0.5MPaa.3. Corrosion test: The industrial corrosion-resistant steel pipes supplied are tested for corrosion resistance according to the standard requirements or the corrosion method agreed by both parties, and there shall be no tendency of intergranular corrosion.4. Process performance test: flattening test, tensile test, impact test, expansion test, hardness test, metallographic test, bending test, non-destructive testing.The process of stainless steel seamless pipe determines its limited performance. Generally, seamless steel pipe has low precision: uneven wall thickness, low brightness of the inner and outer surfaces of the pipe, high cost of fixed length, and pitting and black spots on the inner and outer surfaces are not easy to remove; its detection and shaping must be processed offline. Therefore, it has demonstrated its superiority in high pressure, high strength, and mechanical structure materials.

2025/06/05

PARTNER

cooperative partner

Factory Address:

No. 55, Yunyanshan Road, Songyang County Industrial Park, Lishui City, Zhejiang Province

Sales Headquarters Address:

5th Floor, Building A2, Wanyang Technology City, No. 2999, Nanyang Avenue, Yaoxi Street, Longwan District, Wenzhou City, Zhejiang Province

Sales Hotline:

0086-577-86656878

0086-15906483119

Mail:

cylove168@hotmail.com export3@chinapengye.com

Official website:

en.chinapengye.com

View QR Code

© 2025 Pengye Holding Group Co., Ltd. All Rights Reserved.