Structural Steel Pipe Brand Leader

Yuantai Derun certificate
Home / Process Control

Process Control

Control test itemsControl the detection effectProcessControl and test linksControl inspection content
Selection of manufacturers Ensure raw material manufacturer qualification and product quality 1Raw material manufacturer evaluationComprehensive evaluation of quality, reputation and other aspects, raw material procurement to achieve "quality selection of raw materials"
2verify informationCheck 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                          3Scar checkAvoid "tongue" or "scale", bonded, irregularly shaped raised metal sheets on the surface of the coil
4Crack detectionAvoid open tip bottom cracks on the surface of coil plate
5audit-in-depthAvoid local, obvious metal separation layer on the coil section
6Bubble checkAvoid small holes in the smooth inner wall of circular plate with irregular distribution and different sizes on the surface or inside of coil plate
7Inspection of surface slag inclusionAvoid non-metallic slag on the surface of the coil
8Pitting checkAvoid small, irregular shaped pits and local rough surface on the surface of coil plate
9Cut to checkAvoid straight and thin groove marks on the surface of coil plate
10Scratch checkAvoid slight scratches on the surface of the coil that are straight or curved
11Indentation checkAvoid the surface of the coil plate with different shapes, sizes, discontinuous dents
12Roller checkTo avoid the pressure roller damage, the surface of the plate periodically appear raised or depressed marks
13Rusty spot checkAvoid yellow, yellow-green, or brown spots on the surface of the coil
14Scale inspectionAvoid excessive area of red metal oxide layer on the surface of coil
15Gone with the wind song checkAvoid bending in the longitudinal and horizontal direction of the coil
16Check scythe bendIn line with GB/T 3524 -- 2005 standard (P2) requirements
17The waves to checkAvoid 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)
18Wave wrinkle inspectionAvoid undulating marina bends on one side of the coil along the rolling direction
19Groove checkAvoid the simultaneous curved bending of the coil along both lateral sides
20Thickness checkAvoid uneven longitudinal and transverse thickness of coil
21Burr inspectionAvoid sharp, thin flying spurs on both sides of the width of the coil
22Folding checkTo avoid creases or laps that cause sharp bending of the coil
23The width of the testPrevent width and uniformity not in line with GB/T 3524 -- 2005 standard (P4) or procurement requirements
24thickness detectionTo 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"
25component analysisAnalyze 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)
26mechanical testThe 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      27Incoming inspectionAvoid knocking damage on the surface and edge of the coil
28Shear checkCheck 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
29Guide roll inspectionAdjust guide roller to prevent knife leakage
30Joint inspectionAvoid uneven joints and weld residual height not conforming to GB/ T3091-2015 standards (P8)
31Disc shear inspectionCheck the cutter shaft and cutter sleeve to prevent the uneven width of the cutting tool and raw materials
32Curly checkThe feed should not be too long to prevent curling off
33Inspection of distributing trayPrevent the leakage, burr and buckle of the coil plate
Feeding wheelPut in the coil plate, ensure that the coil plate, into the cage before the preparation34appearance inspectionPrevent the surface and edge of the coil from bumping and damage
Rolled plate cutting headCut off the narrow part of the coil material to facilitate welding35Shear requirementsThe 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 weldingConnect the coil plates of different rolls Together into the cage 36appearance inspectionAvoid 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 production37appearance inspectionTo prevent the surface and edge of the knock damage phenomenon
38Material inspectionPrevent the coil plate from getting stuck or turning over in the cage sleeve
Roller levelingThe raw material is centered with the roll39Roller levelingBecause the coil plate in the cage storage will appear bending, through the five rollers can be relatively flat
Steel pipe formingTo change the coil form from rough to fine (coil into a round tube)40Molding quality inspectionTo 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 formingEnsure the horizontal of both sides of the billet41Extrusion roll inspectionTo 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   42Welding quality inspection   Avoid weak welding, desoldering, cold stack
43Avoid corrugation on both sides of weld
44Avoid weld cracking and static crack
45Avoid weld line formation
 radio-frequency welding     Weld the coil in the shape of a cylinder firmly     46Welding quality inspection     Avoid slag inclusion
47To avoid cracks outside the weld
48Avoid root shrinkage
49Avoid root penetration
50Avoid failure of fusion
51Avoid 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.)
Weld scraping scar Cut and grind the remaining height of external weld 52appearance inspectionPrevent the phenomenon of swiveling seam, free mouth and welding joint dislocation;
Requires no corrugation of the weld and no weld nodules on both sides.
53Weld inspectionEnsure that the weld scratches, color and molding quality meet the requirements of GB/ T13793-2008 (P10)
circulating coolingCooling the welded pipe54Check tank water capacityAccording 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 55Outer diameter inspectionControl in GB/T21835 -- 2008 standard (P5) requirements within the range
56Unroundness checkControl in GB/ T3091-2015 standard (P4) requirements within the range
A rough straighteningEliminate slight bending of steel tube57Observe the aligning equipmentUse 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     58Adjust the instrument before testingSet 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
59First batch inspection after replacement specificationAfter 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
60Testing of welded pipe base metalVisual inspection of steel tube surface quality deficiencies
61Appearance inspection of weldBy 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 feedbackThe 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
Flying saw cutting Setting cutting of butt-welded pipe 63Pipe inspectionThe pipe end shall be guaranteed without burr and inclined mouth
64cut lengthsCheck the speed roller diameter according to the standard and set reasonable data
Steel tube straighteningAdjust the bending of steel tube65appearance inspectionAvoid tube body damage, tube mouth flattening phenomenon; No indentation on the tube surface
Pipe end keepDealing with the burr of the pipe mouth66Pipe inspectionEnsure 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                              67appearance inspectionMake 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
68Internal weld inspectionEnsure 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
69Outer diameter inspectionControl in GB/T21835 -- 2008 standard (P5) requirements within the range
70Unroundness checkControl in GB/ T3091-2015 standard (P4) requirements within the range
71Measuring lengthThe 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)
72Bend detectionAccording 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
73Pipe inspectionEnsure that the pipe head has no burr and the end section meets the requirements of GB/ T3091-2015
74External weld inspectionThe outer weld scar scraping should use arc knife, scraping scar should be arc transition
75Gouges where whole pieces were missing checkAvoid opening at the end of the pipe
76Crack detectionAvoid cracking at the welding bar
77Joint inspectionAvoid joint phenomenon on the welded pipe body
78Cut to checkAvoid serious scratches on the surface of the welded pipe, which will affect the wall thickness.
Negative deviation not less than wall thickness (12.5%)
79Pit testing flatPrevent 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)
80Inspection of pitting surface (pit)Avoid punctate dents on the surface of steel tube
81Inspect inner weld barPrevent the welding bar is not firm, uneven, less than 0.5mm for the welding bar is unqualified
82Burr inspectionAvoid 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.
83Hanging mouth checkAvoid the opening or deformation caused by hook or hoisting, namely "hoisting mouth"
84Reinforcement crack inspectionPrevent the tiny crack in the welding bead
85Scraping scar unevenAvoid 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
86From mouth to checkPrevent 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
87Double skin checkAvoid the surface is not smooth, layered, less meat or uneven phenomenon
88Scar checkAvoid surface solder spots that may cause damage to the base metal
89Sand holes to checkPrevent holes on the surface of steel tube
90Oblique mouth checkThe cross section of the pipe is not perpendicular to the center line, and the end shall meet the requirements of GB/ T3091-2015
91Identity checkAvoid 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   92bending testInspect the welding quality of steel pipes of 2 inches and below to meet the requirements of GB/ T3091-2015 (P7)
93flattening testTo check the welding quality of steel pipes above 2 inches and meet the requirements of GB/ T3091-2015 (P7)
94Pressure tank testTest the performance of the steel pipe pressure groove, in accordance with the CECS 151-2003 trench connection pipe engineering technical specification requirements (P9)
95tensile testTest 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      96Check before unpackingAvoid 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
97visual inspectionVisual inspection of the base metal to prevent cracks, heavy skin, serious rust, sand holes and other defects, serious scratches are not allowed
97Check the end before starting the testThe 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°
98Check the pressure transfer medium (water) before pressurizationAfter 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 testingAccording 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
100Appearance inspection after testEnsure 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
101The report issued byFill 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                        102Identification testConfirm actual wall thickness, specification or mixing of label and welded pipe by measuring and weighing
103Unroundness testEnsure that the unroundness of steel pipe conforms to the national standard GB/T 3091-2015 (P4)
104Measuring length testEnsure the steel pipe length in line with the national standard GB/T 3091-2015 (P5) (6 meters, allowable deviation +20mm)
105Outer diameter inspectionEnsure that the outer diameter of the steel pipe meets the requirements of GB/T21835 -- 2008 Standard (P5)
106Open testCheck whether the pipe end has cut phenomenon
107Fracture testAfter the hammer shock, there is no cracking phenomenon at the welding bar
108Joint inspectionWatch the same tube on whether there is a docking phenomenon
109Rusted pipe surveyVisually check whether there is dirt, paint, oil stains and rusty pipes on the surface of the steel pipe
110Flat pit inspectionVisually check whether the surface of the steel pipe has local pits caused by external forces
111Inspection of pitting surface (pits)Using visual inspection, hand touch the surface of the steel pipe whether there is a point of the bump phenomenon
112Inspect whether the inner welding bar is qualifiedTo 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
113Burr inspectionVisually 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
114Hanging mouth inspectionTo prevent the opening or deformation caused in the hook and hoisting process
115Reinforcement crack inspectionBy 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
116Scraping scar inspectionEnsure that the welding bar scraping scar smooth, circular surface
117Free port inspectionAvoid the phenomenon of folding pressure at the welding seam caused by raw material or mechanical reasons
118Double skin testAvoid the phenomenon of steel tube with double skin
119Circle bamboo-shapedTo prevent the surface of the steel pipe from slubby dents
120Lap weld inspectionVisual inspection to avoid the phenomenon of redundant butt welding on steel tube welding bar
121Scar inspectionVisual inspection to avoid welding spots on the surface of the steel pipe
122Sand holes, inspectionVisual inspection to avoid holes on the surface of steel pipe
123Cut testObtain the pipe body under the gas cutting strapping material to ensure that there is no cutting or damage
124There is not conducive to pickling galvanized sundriesVisual 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 125The concentration of the acidThe content of hydrogen chloride in acid concentration should be controlled at 20%-24%
126Underpickling inspection of steel pipeTo 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 127Packing belt inspectionThe 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
128Trademark checkThe 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

Sign up to get latest update
Please send your message to us
Yuantai team has over 21 years of experience in steel pipe project applications, specializing in the production, manufacturing, and customization of square rectangular, and circular steel pipes. Warmly welcome project procurement managers, individual owners, designers, and overall sellers, etc. Write down your requirements and receive professional quotes and technical support.
  • Only supports .rar/.zip/.jpg/.png/.gif/.doc/.xls/.pdf, maximum 20MB.