YuantaiDerun square rectangular tube has more than 63 patents, which meets the industry standards at home and abroad. The product has passed more than 200 inspection links to control the product quality.
"Firmly do not let a unqualified steel pipe into the market".
| Control test items | Control the detection effect | Process | Control and test links | Control inspection content |
| Selection of manufacturers | Ensure raw material manufacturer qualification and product quality | 1 | Raw material manufacturer evaluation | Comprehensive evaluation of quality, reputation and other aspects, raw material procurement to achieve "quality selection of raw materials" |
| 2 | verify information | Check the information of the raw materials provided by the supplier and enter the goods yard before they are accurate | ||
| Selection of the raw material | The raw material of welded pipe production directly affects the quality of welded pipe | 3 | Scar check | Avoid "tongue" or "scale", bonded, irregularly shaped raised metal sheets on the surface of the coil |
| 4 | Crack detection | Avoid open tip bottom cracks on the surface of coil plate | ||
| 5 | audit-in-depth | Avoid local, obvious metal separation layer on the coil section | ||
| 6 | Bubble check | Avoid small holes in the smooth inner wall of circular plate with irregular distribution and different sizes on the surface or inside of coil plate | ||
| 7 | Inspection of surface slag inclusion | Avoid non-metallic slag on the surface of the coil | ||
| 8 | Pitting check | Avoid small, irregular shaped pits and local rough surface on the surface of coil plate | ||
| 9 | Cut to check | Avoid straight and thin groove marks on the surface of coil plate | ||
| 10 | Scratch check | Avoid slight scratches on the surface of the coil that are straight or curved | ||
| 11 | Indentation check | Avoid the surface of the coil plate with different shapes, sizes, discontinuous dents | ||
| 12 | Roller check | To avoid the pressure roller damage, the surface of the plate periodically appear raised or depressed marks | ||
| 13 | Rusty spot check | Avoid yellow, yellow-green, or brown spots on the surface of the coil | ||
| 14 | Scale inspection | Avoid excessive area of red metal oxide layer on the surface of coil | ||
| 15 | Gone with the wind song check | Avoid bending in the longitudinal and horizontal direction of the coil | ||
| 16 | Check scythe bend | In line with GB/T 3524 -- 2005 standard (P2) requirements | ||
| 17 | The waves to check | Avoid the bending shape of the full length or part of the coil along the rolling direction of the horizontal surface undulating and regular distribution of the protruding (wave peak) and concave (wave trough) | ||
| 18 | Wave wrinkle inspection | Avoid undulating marina bends on one side of the coil along the rolling direction | ||
| 19 | Groove check | Avoid the simultaneous curved bending of the coil along both lateral sides | ||
| 20 | Thickness check | Avoid uneven longitudinal and transverse thickness of coil | ||
| 21 | Burr inspection | Avoid sharp, thin flying spurs on both sides of the width of the coil | ||
| 22 | Folding check | To avoid creases or laps that cause sharp bending of the coil | ||
| 23 | The width of the test | Prevent width and uniformity not in line with GB/T 3524 -- 2005 standard (P4) or procurement requirements | ||
| 24 | thickness detection | To prevent the thickness and uniformity from not conforming to GB/T 3524 -- 2005 standard (P3) or procurement requirements, and to achieve the "wall thickness assurance standard" | ||
| 25 | component analysis | Analyze C, Si, Mn, P and S according to GB/T 4336 standard, and compare the results with the incoming material list to avoid the material not conforming to GB/T 700 standard (P4) | ||
| 26 | mechanical test | The transverse or longitudinal tensile test of the coil was conducted according to GB/T 228 standard, and the results were compared with the incoming material sheet to avoid the mechanical properties failing to meet the requirements of GB/T 3524 -- 2005 standard (P5). | ||
| Rolled plate cutting | Cut the coil to produce different specifications of welded pipe coil | 27 | Incoming inspection | Avoid knocking damage on the surface and edge of the coil |
| 28 | Shear check | Check the hydraulic scissors, shear is not even, the cutting head shall not exceed the effective board surface 2cm, the tail of the coil plate should be processed to the unit | ||
| 29 | Guide roll inspection | Adjust guide roller to prevent knife leakage | ||
| 30 | Joint inspection | Avoid uneven joints and weld residual height not conforming to GB/ T3091-2015 standards (P8) | ||
| 31 | Disc shear inspection | Check the cutter shaft and cutter sleeve to prevent the uneven width of the cutting tool and raw materials | ||
| 32 | Curly check | The feed should not be too long to prevent curling off | ||
| 33 | Inspection of distributing tray | Prevent the leakage, burr and buckle of the coil plate | ||
| Feeding wheel | Put in the coil plate, ensure that the coil plate, into the cage before the preparation | 34 | appearance inspection | Prevent the surface and edge of the coil from bumping and damage |
| Rolled plate cutting head | Cut off the narrow part of the coil material to facilitate welding | 35 | Shear requirements | The narrow part of the coil material shall be cut neatly, perpendicular to the direction of the coil, and the length of the lead part shall not exceed 2cm of the effective surface |
| Rolled plate butt welding | Connect the coil plates of different rolls Together into the cage | 36 | appearance inspection | Avoid uneven joints and weld residual height not conforming to GB/ T3091-2015 standards (P8) |
| Into the material cage | Store a certain amount of raw materials for the unit to ensure the continuity of the unitCar production | 37 | appearance inspection | To prevent the surface and edge of the knock damage phenomenon |
| 38 | Material inspection | Prevent the coil plate from getting stuck or turning over in the cage sleeve | ||
| Roller leveling | The raw material is centered with the roll | 39 | Roller leveling | Because the coil plate in the cage storage will appear bending, through the five rollers can be relatively flat |
| Steel pipe forming | To change the coil form from rough to fine (coil into a round tube) | 40 | Molding quality inspection | To ensure the evenness and symmetry of the opening Angle of the welding seam, the opening Angle can be adjusted according to the pipe diameter. (4 minutes - 1.2 inches of opening Angle is 3-5 degrees) |
| extrusion forming | Ensure the horizontal of both sides of the billet | 41 | Extrusion roll inspection | To prevent uneven, observe the extrusion pressure of the extrusion roll and maintain the same height |
| high-frequency welding | Weld the coil in the shape of a cylinder firmly | 42 | Welding quality inspection | Avoid weak welding, desoldering, cold stack |
| 43 | Avoid corrugation on both sides of weld | |||
| 44 | Avoid weld cracking and static crack | |||
| 45 | Avoid weld line formation | |||
| radio-frequency welding | Weld the coil in the shape of a cylinder firmly | 46 | Welding quality inspection | Avoid slag inclusion |
| 47 | To avoid cracks outside the weld | |||
| 48 | Avoid root shrinkage | |||
| 49 | Avoid root penetration | |||
| 50 | Avoid failure of fusion | |||
| 51 | Avoid leakage welding, false welding, lap welding and other phenomena. (Generally, when the coil passes through the tightening roller, the edge of the coil will melt due to high frequency heating. There will be milky white crystal granular spark during welding, which indicates that the welding quality is guaranteed.) |
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| Weld scraping scar | Cut and grind the remaining height of external weld | 52 | appearance inspection | Prevent the phenomenon of swiveling seam, free mouth and welding joint dislocation; Requires no corrugation of the weld and no weld nodules on both sides. |
| 53 | Weld inspection | Ensure that the weld scratches, color and molding quality meet the requirements of GB/ T13793-2008 (P10) | ||
| circulating cooling | Cooling the welded pipe | 54 | Check tank water capacity | According to different pipe diameter, speed, control water quality, water temperature, water flow, salt content, pH, etc |
| Steel tube sizing | Adjust outer diameter and unroundness of welded pipe | 55 | Outer diameter inspection | Control in GB/T21835 -- 2008 standard (P5) requirements within the range |
| 56 | Unroundness check | Control in GB/ T3091-2015 standard (P4) requirements within the range | ||
| A rough straightening | Eliminate slight bending of steel tube | 57 | Observe the aligning equipment | Use the straightening device to make the steel pipe straight into the next process |
| NDT(nondestructive testing) | Inspect the defects on the surface and inside of the weld that may affect the quality of the steel pipe | 58 | Adjust the instrument before testing | Set relevant parameters; Determine the scanning proportion and flaw detection sensitivity with the contrast test block; Increase the surface compensation to ensure the detection rate of defects |
| 59 | First batch inspection after replacement specification | After each change of product specifications, the first batch of finished products must be inspected. The number of inspection branches should be no less than three. After passing the inspection, the product can be produced | ||
| 60 | Testing of welded pipe base metal | Visual inspection of steel tube surface quality deficiencies | ||
| 61 | Appearance inspection of weld | By visual inspection of the appearance of the weld after cooling, no defects such as weld dislocation, burn, scarring, opening, crack, tendon crack, scraping scar uneven, free mouth are allowed | ||
| 62 | Ultrasonic inspection of metal and weld internal qualitySpot check and feedback | The probe attached to the tube body emits ultrasonic wave, and the instrument receives and analyzes the reflected echo. The sensitivity of the detection reference is adjusted according to SY/ T6423.2-1999, and the type, size and depth of the reflector are determined by the echo wave height displayed on the screen of the instrument. It is not allowed to have any defects that seriously affect the quality of the weld, such as cracks, pores whose echo wave height exceeds 50% of the full screen, non-penetration and non-fusion.Sampling inspection rules: sampling inspection shall be carried out according to 1% of each batch. If any problem is found, record and give feedback in time. Make obvious marks at the defects to facilitate the workers to deal with the corresponding; Increase the sampling rate by 10%. If there are still unqualified products in the sampling inspection process, the unit should be notified to stop and adjust the production process in time |
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| Flying saw cutting | Setting cutting of butt-welded pipe | 63 | Pipe inspection | The pipe end shall be guaranteed without burr and inclined mouth |
| 64 | cut lengths | Check the speed roller diameter according to the standard and set reasonable data | ||
| Steel tube straightening | Adjust the bending of steel tube | 65 | appearance inspection | Avoid tube body damage, tube mouth flattening phenomenon; No indentation on the tube surface |
| Pipe end keep | Dealing with the burr of the pipe mouth | 66 | Pipe inspection | Ensure that the pipe end is smooth and without burr, and ensure that each steel pipe can achieve the "net effect of straight pipe". |
| finished product inspection | Ensure the quality of welded pipe in the workshop meets the standard requirements | 67 | appearance inspection | Make sure that the surface of the steel pipe is smooth, no folding, crack, double skin, lamination, lap welding and other defects exist, allow to have the wall thickness of negative deviation range of scratch, do not allow to have the serious scratch, weld dislocation, burn and scar |
| 68 | Internal weld inspection | Ensure that the welding bar is firm, uniform thickness, in the shape of wire, the inner welding bar should be higher than 0.5mm, threading pipe welding bar is not allowed to have burr | ||
| 69 | Outer diameter inspection | Control in GB/T21835 -- 2008 standard (P5) requirements within the range | ||
| 70 | Unroundness check | Control in GB/ T3091-2015 standard (P4) requirements within the range | ||
| 71 | Measuring length | The length of the steel pipe is 6m. According to the requirements of GB/ T3091-2015, the allowable deviation of the total length of the straight seam high-frequency welded pipe is +20mm. (pipe requirements: 4 minutes - 2 inches 0-5mm, 2.5 inches - 4 inches 0-10mm, 5 inches - 8 inches 0-15mm) |
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| 72 | Bend detection | According to GB/ T3091-2015, the bending degree of the full length of the steel pipe should not be greater than 0.2% of the length of the steel pipe | ||
| 73 | Pipe inspection | Ensure that the pipe head has no burr and the end section meets the requirements of GB/ T3091-2015 | ||
| 74 | External weld inspection | The outer weld scar scraping should use arc knife, scraping scar should be arc transition | ||
| 75 | Gouges where whole pieces were missing check | Avoid opening at the end of the pipe | ||
| 76 | Crack detection | Avoid cracking at the welding bar | ||
| 77 | Joint inspection | Avoid joint phenomenon on the welded pipe body | ||
| 78 | Cut to check | Avoid serious scratches on the surface of the welded pipe, which will affect the wall thickness. Negative deviation not less than wall thickness (12.5%) |
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| 79 | Pit testing flat | Prevent pits and pits caused by external forces in the welded pipe. Enterprise internal control standard (4 minutes - 1 inch, pit depth <2mm; 1¼ inch-2 inch, the pit depth <3mm; 2½ inch-6 inches, the depth of the pit <4mm; 8 inches dent depth <6mm) |
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| 80 | Inspection of pitting surface (pit) | Avoid punctate dents on the surface of steel tube | ||
| 81 | Inspect inner weld bar | Prevent the welding bar is not firm, uneven, less than 0.5mm for the welding bar is unqualified | ||
| 82 | Burr inspection | Avoid irregular excess parts inside and outside the pipe head. Enterprise internal control standard (4 points - 2 inches of burr <1mm; 2½ inch to 4 inch burr <2mm; 5 "- 8" burr <3mm. Note: Burr is not allowed on the net head pipe. |
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| 83 | Hanging mouth check | Avoid the opening or deformation caused by hook or hoisting, namely "hoisting mouth" | ||
| 84 | Reinforcement crack inspection | Prevent the tiny crack in the welding bead | ||
| 85 | Scraping scar uneven | Avoid the uneven welding bar after scraping the scar. The welding bar is not a smooth arc surface. The negative difference lower than the base metal is considered uneven | ||
| 86 | From mouth to check | Prevent the phenomenon of welding seam folding and pressure caused by raw materials or mechanical reasons, the welding bar is not smooth, there are free edges, folding weld dislocation, etc | ||
| 87 | Double skin check | Avoid the surface is not smooth, layered, less meat or uneven phenomenon | ||
| 88 | Scar check | Avoid surface solder spots that may cause damage to the base metal | ||
| 89 | Sand holes to check | Prevent holes on the surface of steel tube | ||
| 90 | Oblique mouth check | The cross section of the pipe is not perpendicular to the center line, and the end shall meet the requirements of GB/ T3091-2015 | ||
| 91 | Identity check | Avoid the trademark stuck on the pipe body and the actual specification of the welded pipe is not consistent or mixed | ||
| mechanical test | Check the mechanical properties of materials | 92 | bending test | Inspect the welding quality of steel pipes of 2 inches and below to meet the requirements of GB/ T3091-2015 (P7) |
| 93 | flattening test | To check the welding quality of steel pipes above 2 inches and meet the requirements of GB/ T3091-2015 (P7) | ||
| 94 | Pressure tank test | Test the performance of the steel pipe pressure groove, in accordance with the CECS 151-2003 trench connection pipe engineering technical specification requirements (P9) | ||
| 95 | tensile test | Test the tensile strength and elongation after fracture of the steel pipe to meet the requirements of GB/ T3091-2015 (P7) | ||
| The water pressure test | Inspect the strength, airtightness and appearance quality of the base metal and weld of the welded pipe | 96 | Check before unpacking | Avoid the discrepancy between the label and the actual specification of the welded pipe or the mixed batch is not allowed to unpack (the same batch number and the same specification are pressed together |
| 97 | visual inspection | Visual inspection of the base metal to prevent cracks, heavy skin, serious rust, sand holes and other defects, serious scratches are not allowed | ||
| 97 | Check the end before starting the test | The surface of both ends of the welded pipe must be smooth and smooth through visual inspection. It is not allowed to have flat head, bend pipe and hanging mouth. The section of the end of the non-burr pipe is perpendicular to the center line. There is no inclined plane and the deviation should be less than 3° |
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| 98 | Check the pressure transfer medium (water) before pressurization | After filling the pressure transfer medium (water) of welded pipe, do not rush to increase the pressure. It is necessary to check whether the system has liquid leakage | ||
| 99 | hydrostatic testing | According to GB/ T241-2007 standard (P2) under the test pressure, pressure speed and pressure transmission medium conditions, stable for a certain time. Visually check the outer surface of the welded tube matrix or the weld seam within the time of pressure stabilization. No leakage or burst is allowed. Visually check the whole welded pipe after the test, no permanent deformation is allowed |
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| 100 | Appearance inspection after test | Ensure that no scratches are allowed; Flat head and bent pipe are not allowed. No oil pollution and other quality problems inside and outside the steel pipe |
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| 101 | The report issued by | Fill in in strict accordance with GB/ T241-2007 standard (P2) and internal special examples (sent in triplicate to the production department, the quality inspection department, with the steel pipe pickling one copy). No fraud is allowed | ||
| Pickling test | Reduce defective quality control in the next process | 102 | Identification test | Confirm actual wall thickness, specification or mixing of label and welded pipe by measuring and weighing |
| 103 | Unroundness test | Ensure that the unroundness of steel pipe conforms to the national standard GB/T 3091-2015 (P4) | ||
| 104 | Measuring length test | Ensure the steel pipe length in line with the national standard GB/T 3091-2015 (P5) (6 meters, allowable deviation +20mm) | ||
| 105 | Outer diameter inspection | Ensure that the outer diameter of the steel pipe meets the requirements of GB/T21835 -- 2008 Standard (P5) | ||
| 106 | Open test | Check whether the pipe end has cut phenomenon | ||
| 107 | Fracture test | After the hammer shock, there is no cracking phenomenon at the welding bar | ||
| 108 | Joint inspection | Watch the same tube on whether there is a docking phenomenon | ||
| 109 | Rusted pipe survey | Visually check whether there is dirt, paint, oil stains and rusty pipes on the surface of the steel pipe | ||
| 110 | Flat pit inspection | Visually check whether the surface of the steel pipe has local pits caused by external forces | ||
| 111 | Inspection of pitting surface (pits) | Using visual inspection, hand touch the surface of the steel pipe whether there is a point of the bump phenomenon | ||
| 112 | Inspect whether the inner welding bar is qualified | To prevent the existence of no internal welding bar (including false welding) or internal welding bar exceed the standard and other problems; Prevent the welding bar is not firm, uneven, or less than 0.5mm is unqualified |
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| 113 | Burr inspection | Visually check whether there are irregular excess parts inside and outside the tube end. After treatment, the burr of pipe end should be less than 0.5mm to be qualified |
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| 114 | Hanging mouth inspection | To prevent the opening or deformation caused in the hook and hoisting process | ||
| 115 | Reinforcement crack inspection | By bending or flattening test, the welding bar of steel pipe is detected to avoid the existence of small cracks. Refer to Article 8 of P6 of Quality Control and Management System for bending test |
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| 116 | Scraping scar inspection | Ensure that the welding bar scraping scar smooth, circular surface | ||
| 117 | Free port inspection | Avoid the phenomenon of folding pressure at the welding seam caused by raw material or mechanical reasons | ||
| 118 | Double skin test | Avoid the phenomenon of steel tube with double skin | ||
| 119 | Circle bamboo-shaped | To prevent the surface of the steel pipe from slubby dents | ||
| 120 | Lap weld inspection | Visual inspection to avoid the phenomenon of redundant butt welding on steel tube welding bar | ||
| 121 | Scar inspection | Visual inspection to avoid welding spots on the surface of the steel pipe | ||
| 122 | Sand holes, inspection | Visual inspection to avoid holes on the surface of steel pipe | ||
| 123 | Cut test | Obtain the pipe body under the gas cutting strapping material to ensure that there is no cutting or damage | ||
| 124 | There is not conducive to pickling galvanized sundries | Visual inspection to ensure no oil stains, paint and other not easy to pickle debris, to prevent leakage of plating | ||
| The pickling steel pipe | Remove sundries such as oxide scale generated on the surface of steel pipe | 125 | The concentration of the acid | The content of hydrogen chloride in acid concentration should be controlled at 20%-24% |
| 126 | Underpickling inspection of steel pipe | To prevent (1) insufficient pickling time, low acid temperature, low concentration (temperature should be controlled in 25-40 ℃, acid concentration of hydrogen chloride is 20%-24%) (2) less shaking times of tube bundle (3) the existence of silicate in furnace welded steel tube | ||
| product packaging | Packed in accordance with the specified number of steel pipes per piece | 127 | Packing belt inspection | The packing of steel pipe is hexagonal, 6 packing belts, all carried out in our factory, both ends of the packing belt from the end of the error of ±10mm, the middle 4 to be equally divided, packing belt welding should be aligned, flat, packing belt does not allow deflection, packing belt should be cut at the junction of 45° Angle, must meet the requirements |
| 128 | Trademark check | The content is accurate, the plane is upward, the finished pipe trademark should be properly pasted on each pipe baffle to align the right side of the first welding packing belt in the middle, and the source Ted embellish writing is clear and not askew |
