Flange Spiral Wound Gasket design requirements and grading

Design requirements of the metal spiral wound gasket

The design of the spiral wound gasket is only a bolt load of sufficient size to compress the gasket to the optimal thickness of the flange connection is valid. To make the mechanical properties of the high pressure gaskets  from the flange connected to the actual ASMEB16.20 provisions: Class150 pressure level, the nominal pipe size 1/2 3/4 of lin the gasket on the flange joint to withstand 25000psi (172MPa) of the uniform bolt stress, the thickness of 4.5mm gasket will be compressed to 3.3 ± 0.13mm; the level of nominal size gasket on the flange joint under 30000psi (207MPa) uniform bolt stress thickness of 4.5mm gasket is compressed to 3.3 ± 0.13mm.

Classification of metal spiral wound gasket

Classification of the spiral wound gaskets with flange connection to the actual the ASMEB16.20 spiral wound gasket compression requirements, based on the analysis of the pipe flanges with spiral wound gasket preload stress, winding the gasket classification technology. and adjust shim structure and control the manufacturing process, the requirements of the mechanical properties of fasteners, so that the flange joint sealing requirements combined with flange to connect the actual, in accordance with ASMEB16 .20 on the metal spiral wound gasket compression requirements, based on the analysis of the pipe flanges with spiral wound gasket preload stress, the classification of spiral wound gasket technology. and by adjusting the gasket structure and control the manufacturing process, so that the requirements of the mechanical properties of fasteners, so that the flange joint of the sealing requirements of the technical

Spiral wound gaskets production process introduction

SUNWELL Spiral wound gasket production process without coherence, can be transient parking; spindle speed gear adjustable, allows different diameter of the gasket with a similar line speed winding; hand wheel adjustment can change the compression wheel position to adapt to different specifications gasket the winding diameter of the piece. Gear train bracket and Tim pulley connected to its activities rocker transition wheel guide rollers, packing tape reel and forming metal reel and make it the same locating datum and the pinch roller feed system to ensure the Zhu round in the same center plane.     The gas source is air compressor, filter regulator to the solenoid directional control valve, pressure regulator to the cylinder to push the piston and connected to the piston rod pinch roller, and the resulting compaction force. helical spring gasket  production process of metal with the tangential tension generated by the friction torque of the electromagnetic clutch is connected to the strip plate, controlled by adjusting the excitation voltage of the controller supply electromagnetic clutch controller set on how to block excitation voltage attenuation factor may be needed to select. Spiral wound gasket production process gasket winding process, the size-line measurement by the displacement sensor. Spiral wound gasket production process sensor gasket width displacement amount converted into a corresponding voltage signal into the controller level preset to 0:00 after the display, and two settings, when either one settings, relay, contactor, release the motor stall, in order to achieve the width of the gasket around the automatic control.     New winding machine is characterized by high precision, and fill with automatic feed, process parameters can be displayed and control, the size of automatic measurement. Therefore, excluding the impact of the manual, spiral wound gaskets  quality and production efficiency has improved significantly. Graphite and other materials wound by the winding machine and the production process is not very complex, but the product quality is the national certification, customers can feel comfortable buying. The spiral wound gasket manufacturing process, metal spiral wound gaskets winding made of a special winding machine. The winding machine according to machine precision processing by the host, feed systems, gas supply and control system composition.

Ceramic Gasket Installation and Safety

4.1, the heat sink selection Note

Ceramic gaskets and thermal gaskets have the following defects (place) must be noted that when the radiator selection: hard material of the ceramic gaskets, but more brittle and less capable of resistance to bending deformation, a very poor radiator surface roughness case, installation is easy to shatter. Ceramic gaskets do the thermal conductivity components, we must require manufacturers to control the surface roughness of the radiator, the indicators of control within the allowable range.

4.2, craft assembly mode (power MOS transistor, for example analysis)

rubber flange gaskets  and power MOS, the radiator during the installation process, involving the technology and safety issues, the following will be introduced one by one.

4.2.1 screws fixation

Installation of the power MOS, due to the screws and the power MOS tube metal part of the creepage distance is limited, so the screws fixed to only be used for functional insulation occasions (radiator not connected to housing land) can not be used for reinforced insulation occasions (housing for the radiator, the safety distance requirements are larger), or safety can not meet the design requirements.

⑴ The using screws fixed TO-247 package power MOS

TO-247 package power MOS only the back of the cooling part only metal, other parts are plastic, secure the power MOS tube, do not do special processing, ceramic gasket (both sides of the required coating of thermal grease) caught in the power MOS transistor and heat sink can be fixed with screws directly to meet the requirements of the functional insulation     ⑵ using screws fixed TO-220 package power MOS

Power MOS tube fixed to the TO-220 package, the need to add a plastic gasket (Figure 3), in Luo nailed to prevent the metal parts of the power MOS screws and heatsink contact, causing a short circuit. Increase the plastic gasket, the power MOS metal parts and screws creepage distance ≥ 1mm. Ceramic gaskets need the same on both sides coated with thermal grease to reduce the contact resistance.     4.2.2 batten fixed

The pressure of the fixed power MOS, mainly for the Safety requirements of the occasion. It has two fixed ways: horizontal pressure and vertical pressure. Figure 4 (a) gives the vertical pressure fixed power MOS transistor (TO-220 or TO-247 package) schematic diagram, Figure 4 (b) shows the horizontal pressure fixed power MOS transistor (TO-220 or TO- 247 package) schematic.

Process design should pay attention to the following three points: ① the pressure of the fixed power MOS to choose not to open the ceramic gasket bolt hole, otherwise it will greatly reduce the power MOS transistor to the heat sink creepage distance; ② ceramic gaskets size must meet the power MOS tube to the radiator of the creepage distance requirements; ③ batten screws directly connected to the radiator, so the pressure must be installed and the insulating sleeve to increase the power MOS tube to the radiator creepage distance.     4.3, the thermal design and structural design considerations

Common type of spiral wound gaskets are monolithic, two-piece. The dual ceramic gaskets for the two power MOS transistors in parallel to install and use. Figure 5 shows the dual ceramic gaskets on the PCB and structural design parameters and their size (TO-247 package power MOS transistor, for example).

The ⑴ pairs of ceramic gasket openings distance is fixed, in the PCB design to maintain the two MOS tube center distance is 19mm; structural design, radiator, two MOS tube opening distance of 19mm.

⑵ If two power MOS transistor power consumption larger radiator installed in the edge of the bottom of the PCB, MOS tube from the radiator edge can not be too close to the size of the size, the specific thermal simulation results of the analysis, otherwise the heat large effect will be greatly reduced.

How to do selection of sprial wound gaskets, corrugated gaskets

1, the spiral wound gasket main body surface does not allow affect the sealing performance of the wounds, gaps, uneven and full of rust defects. The gasket main body we call “basic style spiral wound gaskets”  surface non-metallic belt should be uniform, the appropriate metal with a higher interlayer texture should be clear, but not to reveal the metal band. A gasket pitch of the spiral wound gasket  should be uniform, there should be no lack of fusion or over the melting defect. Strengthening ring surface there should be no burrs, uneven, rust and other defects, the upper and lower sealing surface of the insulating gasket kits main body and to strengthen the ring upper and lower surfaces of the spacing should be equal to strengthen the main ring and gasket should be tightly fixed and can not loose; outside to strengthen the ring and positioning should be maintained between the gasket main body can be appropriately loose.

2, compression rate, spring rate and sealing  corrugated gaskets of important performance indicators, in general, under the premise that meet the requirements of the compression ratio, the higher the spring rate, the better; meeting Rebound Rate standard requirements under the premise of the test value of the compression ratio is bigger as well. Should choose the good sealing performance, compression ratio is moderate and the spring rate as large as possible products.

3, according to working conditions, flange sealing surface selection gasket.

4, the selection of quality management system is sound and effective operation of manufacturers of products, the best selection of holders of special equipment (pressure piping components) manufacturing license and a valid type test report of the company’s products.

Probe into the spiral wound gasket structure and properties

The metal spiral wound gasket structure and process parameters directly affect the performance of the gaskets. Presentation of three different structural parameters of the molding strip, corresponding to the different process parameters, developed by a new spiral wound gasket winding machines as the test sample, multi-functional automatic gasket performance testing machine, mechanical properties (compression rate, rebound rate) and the sealing performance test.

Sample for DN80 PN5.0 the inner and outer rings of flexible graphite spiral wound gasket, test conditions were: preload than pressure 70MPa, 99.9% of test medium nitrogen, medium pressure 5.5MPa, at room temperature, loading, unloading speed 0.5MPa / s . Three factors and three levels of orthogonal test, test, arranged according to the L9 (34) to find the best structural parameters and process parameters match.

Test the gasket and process parameters α – Forming band half-width, α1 = 49.6 °, α2 = 42.1 °, α3 = 34.2 °; Fp – winding tension force = 11.8N Fp1, Fp2 = 14.7N, Fp3 = 17.6N; Fc – winding clamping force, Fc1 = 251.3N Fc2 = 314.2N, Fc3 = 377.0N.

Do 9 different combination of structure and process parameters gasket performance test [3], analysis of variance of the leakage rate data listed in Table 2. It can be seen that the angle 2α of the molding strip and wound compression force Fc on the gasket sealing performance have a significant effect. GB4622.3-93 “spiral wound gasket technical conditions, technical specifications, spiral wound gaskets  compression rate of 18% to 30%, the spring rate ≥ 17% leakage rate of ≤ 1.0 × 10-4 (petrochemical industry recommended).

The goal of optimization is to meet GB requirements under the premise of minimum leakage rate, the highest rate of rebound. Although the trial α2Fp2Fc3 combination [3] to meet the minimum requirements of the leak rate, but the rebound rate is not standard. Therefore, Fp the same level of change have a significant impact on performance level α and the Fc, then the gasket performance test .

flexible graphite gaskets  is entwined with spiral white, forming before the metal and nonmetal flat width from metal and nonmetal forming in the analysis of the well-known foreign seals company like Japan Valqua company, Pillar Company and U.S. Flextallic, and comprehensive determined on the basis of empirical data of the domestic manufacturers. 4.5mm thickness series of spiral wound gasket, metal flat width generally 5.1,5.3, and 5.5mm, non-metallic flat belt according to different materials have different widths. I select only the very wide range of flexible graphite strip as filler, and its width is 5.8 ~ 6.0mm.

Metal flat-band molding, forming round of repression after a pair of special design to ensure the wound gasket thickness 4.5 +0.4 mm and the strip does not gel with clear texture of the surface packing, then forming the strip width B, the flat strip the structural parameters can be obtained through the derivation of the geometric relationship between the width B ‘, the thickness t, forming angle 2α and forming the straight edge width b.

Note the problems of using spiral wound gaskets

Note the use of spiral wound gasket flange gasket problems:

① metal winding flange gasket must not use the low-material gasket to replace the high-material gaskets.

② metal winding flange gasket at high temperature, cryogenic or hot and cold alternating frequently, vibration, strong corrosive media and other harsh conditions, for flat and raised face flange of the metal spiral wound flange seal The gasket is best to install the inner ring of the reasonable material.

③ basic spiral wound gaskets is best not to be used on the convex surface of flange. This is because the basic metal winding flange gasket flange axial compression force, metal spiral wound gasket inner solder joint is easy to open welding, so that will not only cause leaks, and the metal spiral wound flange seal The gasket of soft filler scattered contaminated material and clogging pipes.

(4) metal winding flange gasket sealing elements (ie, the gasket body, or the basic gasket) width than the width of the non-metallic cushion is small. Convex surface, flat and raised face flanges of the metal spiral wound gasket used in the production, not just with the size of the width of the non-metallic cushion is to replace the width dimensions of the spiral wound gasket sealing elements.

Winding flange gasket is a semi-metallic gaskets, standard specification inconel spiral wound gaskets  compressive stress 70MPa about when to achieve a reasonable compression deformation, resulting in good sealing effect; arbitrarily increase the metal the width of the sealing surface of the spiral wound flange gasket body is bound to cause lower compaction force, spiral wound metal flange sealing gasket is certainly not up to standard compression deformation, and therefore can not produce a good seal; if beyond the scope to increase the pressure clamping force would have a deformation of the flange and bolts, can result in leakage.

SUNWELL Successful Produce Plastic Printed Ring Joint Gaskets

SUNWELL Successful Produce Plastic Printed Ring Joint Gaskets

To meet the requirement of different customers, SUNWELL research and produce plastic spraying ring joint gaskets.

The main materials of RTJ is 10# steel, soft iron, carbon steel,etc. Normally we using galvanized,rustproof oil,and other ways to protect Ring Joints, prevent rusting.

Now, we have another methord to do, printed plastic! Not only will not affect RTJ of use and can make gaskets has better protected, delay rustily,prolong service life.

This technology has approval by cutomer, and will provide for high-end users a new antirust solutions.

SUNWELL notice of relocation

Dear Clients:

Thank you very much for your long-term attention and support. Due to business expansion. We are pleased to advise you that our factory had been operated in new plant in April 1st. The original website and e-mail address will be kept still.

Current contact information:


Address: No.500#, West of Beisanhuan Road, Cixi City, Ningbo, P.R.China. 315300

Website: www.sunwellseals.com

E-mail: sales@sunwellseals.com (Mr.Chen), sunwell@sunwellseals.com (Ms.Nina)

Tel: 0086-574-23450019, 23450017

Fax: 0086-574-23450015, 23450010

Thank you & Best Regards

SUNWELL Corp. News Officer.

Shut-off valve of the purchase method and type of

in demanding applications will be made on the cut off valve requirements, cut-off function is an important regulator function and the use of internal quality indicators (cut off level for classification and standards, see related information). In field use, will always be a cut off valve is not good, big leaks and other faults. In addition due to lay a trap, allowing the pressure was too small to open the top and other causes of leakage increases, the vast majority are due to structural valve defects and improper selection.

a structure type selection

dual seal type valve (eg, double seat, double-sealing sleeve valve, etc.) is one of the major shortcomings of large leaks. But before the 1980s, because of the more popular sleeve valve, however, many manufacturers are in a great effort from top to bottom sleeve valve to improve the structure to reduce leakage, it evolved into a very complex structure. So, this brings a lot to be desired: many parts, poor reliability, spares difficult, difficult to maintain, cut off the result is not satisfactory, and so on. In fact, this is the design ideas are misunderstanding, rather than in the body of the “heart” in making such complex changes, it would be better achieved through the external adjustment. Therefore, we should choose a single seal type valve. Thus, sealing problems, reliability issues, maintenance and spare parts are all the solutions of the problem. At this point, the focus of conflict resolution into the media’s unbalanced force on the valve increases the problem, solve it only with a powerful piston actuator stem can be bold. External to this solution is obviously complicated by internal improvements than the much easier way which is not so much the problem, as it is thought the problem. Into the nineties, people began to look for structure is more simple, more reliable sealing shut-off valve. At this time, found that rotary valve than the straight travel valve (single-seat valves, sleeve valves, gate valves) is more superior, so have cut off three eccentric butterfly valve, all-shut-off valve, seal off valve.

compression packing, pump packing, valve stem packing, Graphite Packing, asbestos packing, ceramic packing

Second, the sealing surface of choice

(1) face to face seal:

common piston valve, the sealing surface of the small cone is 60 ℃, 60 ℃ seat is a small cone, the cone width is usually small in between 0.5mm ~ 2mm to seal the two cone must ensure good contact. But in fact, it is always affected by processing errors (like heart degrees, roundness, slant, etc.), the sealing effect is not very satisfactory. Usually this type of valve leakage rate of 10-4, after precision grinding up to 10-6, only to achieve a better seal level.

(2) spherical sealing:

use of the spherical valve seat rotation and fixed a small cone tangent, as the line of contact between them, which compared the effect of a good face seal. Waring’s of full-featured ultra-light valve, butterfly valve, etc. is to use spherical sealing the idea to produce, the leakage rate of 10-6 to 10-8, high-performance butterfly valve can be as high as 10-8 , as well as zero leakage.

Third, the sealing material of choice

(1) soft seal
In addition to corrosion-resistant lining

valve, in general, refers to the soft seal spool valve or valve seat either non-metallic materials (mainly PTFE, and rubber) seal in the form of the valve. Soft sealing valve seal is best, but in the pipe installation, system cleaning that could have left more or less does not clean debris (such as welding slag, iron, etc.), which flows through the valve, it is easy to soft seal spool valve seat or scratch, so that leakage increased, the reliability is poor sealing. Therefore, the choice of soft seal structure must take into account the medium and put into operation before the strict clean flush pipe.

(2) seal

seal surfacing wear-resistant alloy and then shut-off valve is the best choice. In considering the tightness of this approach taking into account the service life and reliability, although the factory index is only 10-6 to 10-8, less than zero leakage sealing effect of the soft, but enough to meet the strict requirements of cut off, and it durable, from an economic point of view more cost-effective.

four, sealing reliability considerations

(1) soft sealing, cutting effect, but not suitable for particle-containing medium, once scratched, leakage will increase dramatically. Therefore, try to use when conditions permit seal. Full-featured ultralight valve seal up 10-7 to 10-8, three eccentric butterfly valves up to zero leakage.

(2) the wear resistance of seals to consider: In addition to selected seal, the leakage requirements of 10-6 on cut-over valve, it should be (or must) wear-resistant surfacing alloy to improve the seal wear resistance, erosion, scratch-resistant ability, improve valve life.

(3) of the heat medium shut-off valve assembly at room temperature, at high temperatures, temperature several hundred degrees. Thermal expansion will change the seal assembly to establish specific pressure. Too tight, sealing surface will be stuck, movement will be severely bruised, strained; too loose, the seal pressure is not enough, two cases leakage will increase dramatically. The best way to solve the elastic seat to absorb the difference caused by this change. There are typically three flexible options: ① spring; ② sheet-style flexible metal ring; ③ hardness and softness of resilient seat. The latter is best, that is flexible to overcome the thermal expansion, but also stiffness and wear-resistant alloys to improve wear heaps face reliability.

(4) erosion of media containing particles, to consider the open spool avoid direct high-speed media erosion. Straight travel valve, butterfly valve do not have this feature, and full-function ultra-light eccentric rotary valve with this feature. In case this should be after the election, two kinds of valves.

(5) for the seal, must have sufficient hardness difference, the same hardness material “each side”, easily scratched.

(6) of the implementing agencies should be increased with the thrust and stiffness, so that moves freely.

five main valve shut-off valve type

by the above analysis, the main valve shut-off valve type as follows, select the cut-off valve should be considered leakage rate, media type, media, temperature, flow coefficient and other parameters and cost. In the following preferred order, first consider the seal, then consider a soft seal.

(1) full-featured ultralight valve

(2) three eccentric metal seated butterfly valve

(3) spherical double eccentric butterfly valve seal

(4) ball valve

(5) eccentric rotary valve

(6) single seat

(7) single-sleeve valve seat

(8) soft seal valves

six, high temperature, high pressure, high pressure, large diameter cut-off valve selection

high temperature, high pressure, high pressure, large diameter cut off is a relatively common problem, mainly due to the lack of pressure also has to allow large, cut off, high temperature expansion cards of the valve, such as high pressure steam regulation and cut off, due to pressure large (1 ~ 3mpa or larger), large-caliber (dn200 ~ 300), had to use the balanced double seal structure (such as two-seater or double seal valve sleeve valve), the special treatment, the leakage rate of up to 10-4, and then improve on the difficult, and full-function ultra-light composite valve performance, and can be a better solution to this problem, the leakage rate of 10-6 to 10-7 or more.

Standard pump shaft runout and alignment

1, beating the standard shaft

1) journal taper shaft with ellipticity less than 1 / 2000. But the maximum shall not exceed 0.05mm, and the surface may not have scars.

2) exceeds the allowable value of shaft bending or heating mechanical method can be used for alignment. Axis allows the beat value in the table below (unit: mm):

shaft at the central axis (1500 rev / min) the central axis (3000 rpm / min) multi-stage pump

≤ 0.02 ≤ 0.10 ≤ 0.08 ≤ 0.05

2, the pump shaft alignment method

1) cold direct method

(1) the use of hand-screw press alignment

smaller shaft diameter and bending is large, this method can be used. First axis on the block triangular gap Jiazhu, or on the machine on both ends of the shaft to withstand the use of thimble, and then curved convex vertex axis upward. Raised with the screw press to suppress vertices, the top down pressure, up until the shaft alignment.

(2) the use of twisted rods beat alignment

larger shaft diameter and bending is small, you can use this method. This method is the use of twist stick to beat the cold bending axis concave surface of the shaft extension of the more straight here. Twist rod shaft by the hardness is lower than the hardness of the material, or hardness of the material in inlaid copper sleeve, twist the edges of bars must have a garden corner.

in straight axis, the axis of the concave side up, and support to live the maximum bending of convex vertices. Down at both ends of the pressure with tension device, then use 1-2 kg of a hammer twist rod, the axis of the concave material by beating the extension. Twist hit, the first from the lowest concave central to beat, gradually move to both sides, and one-third of the arc along the circumference on, but more to the center tap density should be greater.

axis alignment is usually proportional to the quantity and frequency of beat. Note that the first beat, the axis alignment faster, later slower. Beat should be careful to twist stick, do not damage the shaft surface.

(3) compared with the screw jack straight

When the amount is not significant bending axis (long axis less than 1%), lower in cold compared with the screw jack straight. Straightening, taking into account the rebound shaft to overcorrection of some, in order to ensure more upright axis after correction. Accuracy of this method can reach 0.05-0.15 mm per meter.

(4) wire rope straightening

2) local heating method

the curved convex upward, wrapped in a cloth around the stone, then use a blowtorch or gas welding and rapid heating. Heating temperature is about lower than the critical temperature of 100 ℃ materials around. Emergency heat, due to plastic deformation of metal to shorten the length of the surface, despite the tension in the cooling, but has not restored its original state, and resulting bending in the opposite direction with the original anti-bending, so flat and convex to straight axis purposes. Concave heated in the fire as its thermal expansion to help stretch, the better.

heating method, should be uniform, equidistant (about 20 mm away from the axial plane), spin out from the center outward, and then from outside to center screw to keep the temperature uniform.

heating area and shape with axial openings (short axial length and radial) method of heating, the temperature uniformity of the radial direction, so that the shaft is not easy to create a distortion. The radial openings (radial and axial length shorter) heating method, the direct-axis effect is remarkable.

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alignment, the first two axis flat on the bearing, so that the curved part of the convex upward, and bend in the shaft of the largest stone with a wet cloth bandage. This stone cotton axial or radial openings 0.15d × 0.2d opening 0.35d × 0.2d (d axis diameter) of the rectangular mouth, and then use the oxyacetylene flame in the opening heat 3-5 minutes (use a strong torch, and the oxygen pressure to 4-5 atm), temperature of 500-600 ℃ after covering with a dry cloth to heat stone at, heat 10-15 minutes, and finally blowing with compressed air, so that the rapid cooling. Axis of bending changes measured by the dial indicator. One can not be repeated straightening, straightening, the axis should be heated at low temperature annealing, and slow rotation about axis heated to 300-350 ℃, maintained at this temperature for more than an hour, and then ligation of hot asbestos cloth Department, it slowly cooled to 50-70 ℃, so that you can eliminate the internal stress.

axis in alignment with the process of change in the amount of material properties on the shaft itself. Heating, shaft bending deflection increases to the maximum, which is due to expansion of convex Centre at the Ministry of heated metal. After cooling, shaft bending deflection gradually decreases to a minimum, which is due to the rapid cooling of metal protruding fibers to shorten the Ministry of the results.

3) stress relaxation method

principle is that there are relaxation properties of metallic materials, namely, the stress components at a high temperature drop at the same time, parts of the elastic deformation and plastic deformation to reduce the proportion of increase, then if the load with a certain direction, you can control it the deformation direction and size. When lifting the load, due to plastic deformation, it is based, so very little rebound, so as to achieve the purpose of direct axis. Multi-purpose induction heating coil of tools, straight shaft, should be annealed. This method is used for large shaft.

4) mechanical heating straight axis method

advance shaft, convex side up, and then applied axial load will bend under the pressure, causing compression stress in the convex, concave and then place in a heated, can also direct axis. This method applies only to the smaller curvature axis