【 Weak current College 】 on KBG tube and JDG pipe application problems

Summary: adoption of the KBG pipe and tube features and JDG connection method of summarizing its construction quality control and quality problems for the current construction of proposed mitigation measures.
Keywords: KBG tube JDG pipe connection quality control
Today, KBG pipe and tube construction with its JDG, convenient, comprehensive price cheap, superior performance, specifications, accessories, etc., in 1kv construction electrical engineering in his widely. However, both types of thin-walled steel pipe in the building materials market and works in use, there is confusion, authenticity, title, such as the phenomenon of construction technology confusion, seriously affecting the wire quality piping engineering. I had been in 1998, 2000, attended the two types of steel conduit "wire pipe construction and acceptance of" the validation Conference, and for many years engaged in the practice of their works; are these two types of steel tubes provide a brief comparison of the main features which, in turn, sets out quality control and project quality common failing preventing and controlling measures, would like a peer reference.

1.KBG pipe and the characteristics of JDG tube
1.1KBG tube
1.1.1KBG tube ontology
KBG-short thin-walled steel pipe, pipe KBG. Catheter using high-quality cold-rolled strip steel, high-frequency welded pipe mill automatic welding seam forming and zinc-coated on both sides. Pipe wall thickness uniformity, high volume welding roundness and fitting tolerances combined with good weld small and round, the tubes estuary smooth edges. There are 16, Φ Φ 20, 25, Φ Φ 32, Φ 40 five specifications, tube thickness 1mm or 1.2mm respectively, auspicious sees in table 1. Duct length are 4m factory.
Table 1 KBG tube size (mm) specifications Φ Φ Φ 16 20 25 32 40 diameter Φ Φ D 16 20 25 32 40 thickness d 1.0 1.0 1.2 1.2 1.2 1.1.2 connectors and connections
1.1.2.1 connector
1) straight fittings for pipeline segments of tube and pipe. Joints of pipe inner and outer diameter of the Guide, there is a fitting and tube wall thickness consistent depth of Groove.
2) bend fitting for pipe and tube bending section of pipe. Bend fitting made of high quality tubes with roll formed, 90 ° bend. There are four times six times curved, bent, the bending radius are the diameters of 4 x, 6 x.
3) male connector, for pipe connections between the boxes. There is a fitting and tube wall thickness depth consistent Groove, connector and one end of the catheter is connected to the same straight fittings, connectors and connection box, one end of the inner processing thread threads, outline a hexagon with a claw nut.
1.1.2.2 connection mode 4)
5 pipes and pipe connection): insert a catheter directly into the straight pipe joints or bend fitting, KBG for withholding purposes in connection.
6) tubes and connections: first threaded fitting and junction box purposes thread connection, and then insert the tube threaded fitting at the other end, by withholding in threaded fittings and pipe joints purposes of withholding.
1.2JDG tube
1.2.1JDG tube ontology
TUPE galvanized steel conduit, hereinafter referred to as JDG. Catheter using high-quality cold-rolled strip steel, high-frequency welder group auto weld forming, double-sided galvanized protection; uniformity, high volume, and roundness welding fitting tolerances combined with good weld small and round, smooth edges; the spout with supporting pipe Bender bending deformation small during cross section. Tube factory in total length 4m Φ Φ 16, 20, 25, Φ Φ 32, Φ 40 five kinds of specifications. Standard pipe wall thickness to 1.6mm, embedded, suspended ceiling installation are applicable; other-tube wall thickness for 1.2mm, only applies to the suspended ceiling installation. See table 2.
Table 2 JDG tube size (mm) specifications Φ Φ Φ 16 20 25 32 40 diameter Φ Φ D 16 20 25 32 40 d standard wall thickness – 1.6 1.6 1.6 1.6 other type 1.2 1.2 1.2 — — — —
1.2.2 connectors and connections
1.2.2.1 connectors
1) straight fittings for hose and tube connections. There is a fitting with rolling pressure out of the Groove, formed by the taper, catheter plug orientation to ensure the tightness of the notch depth and conduit wall thickness, without prejudice to the thread. Connectors at both ends with a belt tightening screw threaded holes. Tightening screw fastening for tailor-made, forcing a hexagonal screw-terminal and a recessed, conical shaped at the other end; close to tighten screw-end with a diameter smaller "neck".
2) male connector, for pipe connections between the boxes. Connectors and terminal box connections end with a claw nut and a hex nuts; and one end of the catheter connections, there is a belt tightening screw threaded holes for fixing screws and threaded hole structure dimensions and straight fittings are the same.
1.2.2.2 connection methods
1) pipe and tube connections: first catheter and straight fitting plug position, continued with tightening wrench to tighten the fixing screw until the turn off the "neck".
2) pipe connection with box: Rotary screw joints claw nut and placed wall junction box with tightening wrench allowing claw nut and hex nut miles clips immediately box. Then move the tube with threaded connector, connect the other end of the process approach with the catheter and direct connection of the fitting.
2. construction quality control
2.1 strictly distinguish between KBG tube and pipe JDG.
As mentioned earlier, KBG tube and pipe, although JDG are galvanized thin-walled steel pipe, but there are three major differences:
1) connection for withholding-KBG, JDG tube for tightening type.
2) pipe turn approaches, KBG tube is the use of curved pipe fitting, JDG is to use pipe Bender bending.
3) pipe wall thickness is not exactly the same, KBG pipe pipe wall thickness, Φ Φ 16-, 20 mm, for 1.0mm Φ Φ 25, 32, Φ 40 m m for 1.2mm; JDG tube is divided into two types, standard Φ Φ 20, 25, 32, Φ Φ 40 mm are 1.6mm, ordinary Φ Φ 16, 20, 25 m m Φ, pipe wall thickness to 1.2mm. Standard applies to embedded laying and ceiling installation, normal applies only to the ceiling.
2.2 strengthen pipe approach quality approval management.
KBG tube and pipe approach quality acceptance JDG, primarily examine the product test reports and the factory certification; check the outer wall of the tube, should be good for zinc coating should be uniform, and corroded surface flaking; pipe and connection accessories should smooth surface, no crack, Burr, Burr, sand, and other defects; pipe and the wall thickness of the connected accessories should be uniform, smooth spout, detects the tubing and pipe wall thickness should be consistent with the catheter size requirements of the table.
For JDG tube, still needs to check the tightening screw meets the requirements: thread should be neat and smooth, with a good, solid, rotating ejector fixing broken "neck" size is correct.
2.3 seriously implement construction and acceptance.
2.3.1KBG pipe construction techniques
1) straight pipe connection, two tube insert straight fitting centres on both sides of the concave-shaped trough; corner connection nozzle insert curved pipe joint AU-slot on the side.
Level 2) pipe laying, withholding point to the top, below the pipeline; pipeline laying vertically, the withholding of points to the left and right side of the pipeline.
3) pipes and fittings, connections of withholding point depth should not be less than 1.0mm.
4) wire line and grounded to Earth wire card connection should be used to prohibit fusion-welded connection.
2.3.2JDG pipe construction techniques
1) pipe connection, two tube connecting end plugged straight fitting intermediate, close to the concave-shaped trough, on both sides, with a tightening screw position, tighten the screw in axial direction until the nuts.
2) pipe bending, use a dedicated pipe Bender job.
3) wire line and grounded to Earth wire card connection should be used to prohibit fusion-welded connection.
3. the quality problems and their prevention
3.1 quality defects
1) KBG tube and pipe appellation JDG. Since the advent of earlier, KBG tube JDG pipe in, are usually used to be two types of pipes are collectively referred to as KBG pipe, even in some provinces, the city of installation work to budget fixed price list also collectively of the KBG. Resulting in the tubing, as defined in the annex, construction technology, building materials market cross hybrid on counterfeit products.
2) KBG pipe wall thin, pipe bending should bend fitting is used. Bend fitting is really a section of pipe. Some construction pipe chosen is KBG tube, but with pipe Bender bending, causing pipeline radians uneven, SAG and creasing and other defects.
3) are relatively thin-walled KBG catheter impersonate JDG catheter, pipework connections with tight stereotypes connector. For example, Φ 20 m m K B G tube, pipe wall thickness 1.0mm, tightening connection, which will inevitably lead to catheter tightening at SAG deformation and the connection is not tight is not strong, resulting in a pipe connection loose disconnect are not uncommon.
4) adoption of the so-called JDG catheter, its tightening screw is not in compliance with the requirements of product design, supplier factories to ordinary city purchase screw off as alternative. In construction, this kind of screws is not possible to duct connection adapter connection, it certainly will not be able to reach the JDG catheter construction process the required screw tightly set screws until the turn off screw "neck".
5 pipes and grounding connection), the individual's use of welding, pipe deformation and destruction, galvanized tube Welding residual scar removal, etc.
3.2 prevention measures
1) rationalize procurement supply channel, keep the good entry materials quality approval.
2) strict implementation of construction and acceptance, KBG-type thin-walled steel pipe bending its pipeline to elbow joints, prohibiting the use of straight pipe to pipe Bender bending.
3) KBG-type thin-wall steel pipes shall be in the accompanying annex, pipeline connection shall be appropriate for direct fitting or elbow joints, taboo use tightening type connector.
JDG-4) thin-walled steel pipe its connector on the tightening screw, and must be consistent with the product design requirements of special screws. Before the construction, to strengthen this type of material testing.
5) for any made of galvanized steel wire protective pipe line, strictly forbid using fusion-welded construction, pipeline and grounding connections shall Earth wire card connection.
4. conclusions
KBG-type thin-walled steel conduit and JDG-type thin-wall steel pipes shall be related to the construction of the acceptance inspection and installation material approach laying construction and engineering quality acceptance, ensure the quality of the project.