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Process Control

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"
Selection of manufacturers		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
Into the material cage		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.)
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.
Weld scraping scar	Cut and grind the remaining height of external weld	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
Steel tube sizing	Adjust outer diameter and unroundness of welded pipe	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
Flying saw cutting	Setting cutting of butt-welded pipe	63	Pipe inspection	The pipe end shall be guaranteed without burr and inclined mouth
Flying saw cutting	Setting cutting of butt-welded pipe	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)
		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%)
		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)
		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.
		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°
		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
		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
		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
		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
		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
		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%
The pickling steel pipe		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
product packaging		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

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