FAQ

Q: Do you have an O-ring that can be used in 400℃-500℃? [ 3640 3641 ]

A: The metal hollow o-ring can be used.

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Q: Can the compressed non-asbestos fiber sheet gasket be used in inflammable gas [ 6500 6500AC 6502 6503 6503AC ]

A: The compressed non-asbestos fiber sheet is a product that mixes various materials such as organic fibers, inorganic fibers, fillers and rubber and then processed into a sheet, so there is a small cavity within the gasket in terms of its structure. As a result, it is relatively prone to leakage in the case of fluids that are easily permeable like gaseous matter with small molecular weight. Therefore, we do not allow usage in inflammable gas taking into consideration cases in which even small leakage such as of flammable gas is unfavorable.

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Q: Are there any precautions when using the full-face gasket? [ 6500 6500AC 6502 6503 6503AC ]

A: There are cases in which full-face gaskets cannot be sufficiently tightened with a flat face flange or the like due to its wide gasket contact cross section. As such, we recommend a normal ring gasket, but the usage of the full-face gasket is allowed if sufficient tightening is possible such as the gasket seat being raised face.

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Q: Please tell me how to estimate the tightening torque of the compressed non-asbestos fiber sheet gasket [ 6500 6500AC 6502 6503 6503AC ]

A: The tightening torque is calculated by the calculating formula below using the recommended tightening stress described in the catalog.

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Q: What kind of product is 6540HP? [ 6540HP ]

A: Just as in 6540H, the basic structure of 6540HP consists of flexible graphite pasted on a serrated gasket surface, but the dimensions of HP are set for standardized flange and it can be used with the same tightening force as a conventional compressed non-asbestos fiber sheet.

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Q: Please introduce the spiral wound gasket that can be used for aluminum flange [ 6590 6591 6592 6596 6590VC 6591VC 6592VC 6596VC ]

A: We recommend the usage of a spiral wound gasket that uses an aluminum hoop for soft flanges like aluminum and copper alloy flange. However, the thickness must be 4.5t.

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Q: Please tell me about spiral wound gaskets that are used in extremely low temperature [ 6590 6591 6592 6596 6590VC 6591VC 6592VC 6596VC ]

A: The bolt material that is used in extremely low temperature is usually stainless, so it will have a weaker tightening force than the bolts like SNB7 that are often used in spiral wound gaskets. We therefore recommend 6596V when the tightening force is insufficient. It is also possible to use 6596V if sufficient tightening force can be added.

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Q: Is it possible to manufacture the spiral wound gasket in sizes other than the standard size? [ 6590 6591 6592 6596 6590VC 6591VC 6592VC 6596VC 7590 7591 7592 7596 8590 8591 8592 8596 M590 M591 M592 M596 M590L M591L M592L M596L ]

A: Yes, it is possible for both the gasket main unit and inner & outer rings as long as you specify the size. However, please contact us because there is a range in which manufacturing is possible such as for the width.

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Q: What are the precautions when coating the gasket paste to 7020 and 7026? [ 7020 7026 ]

A: The surface is coated when the flange accuracy is low, but you need to be careful about the tightening force because it will become slippery. If you will coat the surface, use the New VALFLON(TM) Paste and coat it as thinly and evenly as possible.

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Q: What are the precautions when using a soft sheet gasket? [ 7GP61 7GP61S 7GP66 7GP66S ]

A: VALQUA' PTFE resin such as the VALFLON (TM) SOFT SHEET GASKET is made to be flexible by lowering the density. A tightening force of more than a certain amount is necessary because there is a need to compress it to a density that can be sealed.

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Q: Can inflammable gas be used with GF300? [ UF300 GF300 MF300 SF300 ]

A: Yes, it can be used. It can be used as long as permeation leakage is prevented by using New VALFLON (TM) Paste.

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Q: Is it better to coat a gasket paste on high performance non-asbestos sheet gasket? [ UF300 GF300 MF300 SF300 ]

A: We recommend coating a gasket paste on the surface of the gasket that comes in contact with the flange and the cut surface of the gasket inside diameter side for gas seals. Also, please use the New VALFLON (TM) Paste for the gasket paste. In particular, No.6 and No.6M cannot be used because they have poor compatibility with the surface of the high performance non-asbestos sheet gasket.

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Q: May hot bolting be performed on the high performance non-asbestos sheet gasket? [ UF300 GF300 MF300 SF300 ]

A: Yes, it may be performed. Performing hot bolting has an effect of maintaining the tightening force. However, a reduction of rigidity occurs at high temperatures because PTFE of the constituent materials has thermoplasticity. We therefore recommend to perform hot bolting by control of tightening force while paying attention not to cause damage by excessive tightening.

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Q: Why are the GF300 Series as well as 7020 and 7026 (fluorocarbon resin gasket) described to be unsuitable for polymerizable monomers? [ UF300 7020 7026 GF300 MF300 SF300 ]

A: There are cases in which the polymerizable monomer causes expansion by permeating into the gasket and polymerizing inside it, which results in the gasket to be damaged. We recommend the use of a spiral wound gasket with inner & outer rings or a metallic gasket, which hardly allow polymerizable monomers to permeate, or difficult to damage even if they permeate and polymerize.

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Q: Can the high performance non-asbestos sheet gasket be also used on large diameter flanges that exceed the width and length? [ UF300 7020 7026 GF300 MF300 SF300 ]

A: Yes, it can also be used on large diameter flanges because it can be bonded.

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Q: Which gasket should I use for the exhaust heat duct? [ N214 N314 N520 ]

A: We usually recommend the VALQUATEX Gasket (N314 and N214), but some leakage will occur.  If you require sealability, please coat a gasket paste on the metal jacketed gasket.

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Q: There seems to be cases in fluorocarbon resin envelope gaskets in which fluids permeate through the jacket and damage the core. Do you have any countermeasures for this? [ N7030 N7031 N7035 ]

A: Please consult us for countermeasures such as increasing the thickness of the PTFE jacket, making the exposure area thicker (only for N7035) and improving the chemical resistance of the core material.

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Q: Do you have sheet gaskets that can be used up to a high temperature in strong alkali like black liquor or sodium hydroxide? [ UF300 ]

A: We recommend UF300.

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Q: I want to control the width of the opening in the flange such as with a sheet gasket. How should I do this? [ 6590 6591 6592 6596 ]

A: Control with width of the opening in the flange is prone to cause a margin of error and an accurate tightening stress cannot be obtained. It is effective for uneven tightening, so please use it in conjunction with control of tightening torque.

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Q: Why does leakage occur during stop or re-operation even though there are no problems during plant operation? [ 6590 6591 6592 6596 6590VC 6591VC 6592VC 7591 ]

A: Expansion and contraction of the flange, bolt, pipe and the like will occur due to temperature changes. As a result, a tendency of reduced tightening force in the gasket main unit is often observed when the temperature decreases (including low temperature at the time of initial re-operation), and leakage occurs due to relaxation. We therefore generally recommend a retightening of the gasket before re-operation after the first heat addition.

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Q: Please tell me about the difference in the gasket dimensions between flanges of the JPI and ASME/ANSI standards. [ 6590 ]

A: JPI basically quotes from ASME/ANSI, so there are cases in which the dimensions differ slightly due to rounding error during the millimeter conversion of the original number. We understand that, in actual use, the function of the gasket is fulfilled to an equivalent degree by both dimensions.

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Q: Is retightening effective when leakage occurs? [ 6590 6591 6592 6596 6590VC 6591VC 6592VC UF300 7590 7591 7592 7596 8591 GF300 MF300 SF300 ]

A: Yes, it is effective. We ask that retightening during leakage be performed after relieving internal pressure. However, there are also points to keep in mind for each product, such as the possibility of damage as a result of temperature-induced hardening in the case of a compressed non-asbestos fiber sheet.

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Q: I am not sure which gasket to select, so could you select it for me? [ 6590 6591 6592 6596 6590VC 6591VC 6592VC UF300 7590 7591 7592 7596 8590 8591 8592 8596 M591 M596 7020 GF300 MF300 SF300 ]

A: If you contact us together with your operating conditions, we will recommend an appropriate product based on our technician's selection.

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Q: What should I use to cut the gland packing?

A: The gland packing can be cut with a sharp blade such as a standard cutter knife or kitchen knife of medium size or larger. Also, a guillotine packing cutter, which is a dedicated cutting tool that combines a scale and a cutting machine, is sold by Garlock, our partnering company in the U.S.

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Q: Which is better for cutting the gland packing, bias cut or straight cut?

A: When looked at in one-ring units, both bias cut and straight cut have their advantages and disadvantages, such as the bias cut being less prone to leakage due to a long cut surface and the butt portion of the cut surface being less prone to shifting in the straight cut, but basically because this is a product that is used with multiple overlapping layers, there will be no difference in terms of using either cutting method.

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Q: Why is the gland packing for pump used with leaking liquid?

A: Unlike a mechanical seal or lip packing, lubrication and coolability of the contact surface are secured by using it with leaking liquid. Using it without leaking liquid may result in the seizing, damage or short life of the packing. In addition, the amount of leaking liquid varies depending on the operating status of the pump and the performance of the gland packing that is used.

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