Precautions For Use Of Metal Wound Grommets

- Nov 06, 2017-

Precautions for use of metal wound Grommets
Metal Winding Grommets is widely used in petroleum refining, petrochemical, chemical, thermal, gas, nuclear, aerospace, textile, pharmaceutical and many other industries equipment, process piping static sealing parts.
1, Metal-wound Grommets' sealing elements (ie Grommets or Grommets) should be narrower than the width of the non-metallic soft Grommets. When making Grommets with metal for use in relief, flat and raised face flanges, the width dimensions of the metal wound Grommets seal can not be replaced by the width of the non-metallic soft Grommets. Because the metal wrap Grommets is a semi-metallic Grommets, the standard Grommets compressive stress at 70MPa only when the reasonable compression deformation, resulting in good sealing effect.
If you arbitrarily increase the width of metal winding Grommets on the side of the body, will inevitably lead to reduced pressure, metal winding Grommets certainly can not achieve the standard amount of compression deformation, and therefore can not produce a good seal; if the over-range to increase pressure, but also inevitably Large deformations of the flange and bolt result in leakage.
2 basic type metal winding Grommets best not to use sub-convex surface flange. This is a prismatic metal-wrapped Grommets with an axial compression force on the flange. The Grommets inner ring joints are easily weldable, which can not only cause leaks, but also that Grommets' soft packing can contaminate the material and block the pipe.
3 in the high temperature, cold or hot alternating, vibration, strong corrosive media and other harsh working conditions, for the plane and the flange face of the metal winding Grommets best to install a reasonable material inner ring.
4. Never use high-quality Grommets instead of low-quality Grommets. For example, large-scale petrochemical cracker waste heat boiler inlet, and some operating temperature reached 798 ℃, so metal winding Grommets metal band and the inner ring must be selected with no less than OCr25Ni20 material, but can not be replaced with 0cr18Elil0i, ring material available. 0r18Ni10Ti, but not available 0CrlM9, prisoners may produce high temperature creep.
Metal winding Grommets its characteristics are: compression, rebound performance is good; with multi-channel sealing and a certain self-tight function; for the surface of flange compression surface is not sensitive, non-bonding flange sealing surface, easy to center, So disassembly and easy; can partially eliminate the pressure, temperature changes and the impact of mechanical vibration.
The performance requirements for metal wound Grommets include the following:
1, to strengthen the ring Unless otherwise agreed by both sides of supply and demand, the inner ring material should be the same with the metal strip material; positioning ring material A3 steel, subject to anti-rust treatment.
2, Metal Winding The main body of Grommets is made of V-shaped metal tape and non-metal tape overlapped and continuously wound. Metal tape and non-metallic tape should be close fit, uniform level, no wrinkles, voids and so on.
3, metal winding Grommets primary and secondary winding should be the main body of 3 to 4 laps between the metal strip is not filled with non-metallic tape, the nominal diameter of more than 1500 mm of metal winding Grommets, the number of empty rings may be appropriate to increase the ring Grommets, after the end of the body should continue to weld around the metal with 2 to 4 laps. Adjusting clearance and positioning for assembly of the outer ring. These turns of metal tape do not count as the outside diameter of the metal wound Grommets.
4, metal winding Grommets main body, outside the number of solder joints should be consistent with the provisions of the standard, the beginning and end solder joints not less than 3:00, solder joints spacing of not less than 10 ~ 15mm.
5, metal winding Grommets inner ring, positioning ring by the entire sheet metal stamping, car, or by welding, welding after the car system, the torus should be smooth: ring groove and the inner and outer circles should be concentric, and the two ends should be symmetrical .
6, with the inner ring of metal winding Grommets, can be directly wound on the outer ring made of the inner ring. Special tools can also be used to the inner ring and Grommets main body tightly.
7, the positioning ring and Grommets main body should have the appropriate assembly clearance.
8, Metal Grommets body wrapped, the sealing surface does not allow further machining or pre-pressure treatment.

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