Category: Technical Information

Categories: Technical Information

Style CG & CGI to suit AWWA C207 Class E Slip-On and Welded Neck Flanges

Dimensions for style WR/WRI to suit AWWA C207
Class E Slip-On and Welded Neck Flanges

Class 125
Nom.
Pipe
Size
Inner Ring I.D.WindingCentering Ring Outside Dia.
I.D.O.D.
222222.75024.00026.000
262626.50027.75030.500
282828.50029.75032.750
303030.50031.75034.750
323232.50033.87537.000
343434.50035.87539.000
363636.50038.12541.250
383838.50040.12543.750
404040.50042.12545.750
424242.50044.25048.000
444444.50046.37550.250
464646.50048.37552.250
484848.50050.37554.500
505050.50052.50056.500
525252.50054.50058.750
545454.50056.50061.000
606060.50062.50067.500
Class 175
Nom.
Pipe
Size
Inner Ring I.D.WindingCentering Ring Outside Dia.
I.D.O.D.
     
262626.50027.75029.125
282828.50029.75031.125
303030.50031.75033.375
323232.50033.75035.375
343434.50035.87537.500
363636.50037.87539.500
383838.50039.87541.500
404040.50042.00043.500
424242.50044.00045.875
444444.50046.00047.875
464646.50048.00049.875
484848.50050.12551.875
505050.50052.25053.875
525252.50054.37556.125
545454.50056.37558.125
606060.50062.50064.125

DIMENSIONS IN INCHES.

Class 250
Nom.
Pipe
Size
Inner Ring I.D.WindingCentering Ring Outside Dia.
I.D.O.D.
262626.50027.75032.750
282828.50029.75035.250
303030.50031.75037.500
323232.50033.87539.750
343434.50035.87541.750
363636.50038.12544.000
383838.50040.12546.000
404040.50042.12548.250
424242.50044.25050.750
444444.50046.37553.000
464646.50048.37552.250
484848.50050.37558.750
Class 350
Nom.
Pipe
Size
Inner Ring I.D.WindingCentering Ring Outside Dia.
I.D.O.D.
262626.50027.75029.625
282828.50029.75031.625
303030.50031.75033.875
323232.50033.87535.875
343434.50035.87537.875
363636.50038.12540.375
383838.50040.12542.375
404040.50042.12544.375
424242.50044.25046.625
444444.50046.37549.000
464646.50048.37551.000
484848.50050.37553.000
525252.50054.25057.375
545454.50056.50059.375
606060.50062.50065.375
666666.50068.50072.500

DIMENSIONS IN INCHES.

 
Contact us for more information regarding AWWA C207 Class E Slip-On and Welded Neck Flanges.

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Categories: Technical Information

A Spiral Wound Gasket is the most widely used common metallic gasket used in industrial applications involving a range of pressure and temperatures. They are popular in the oil and gas, chemical, petrochemical, power, and food industries and prevents leak through flange joints. The concept of spiral wound gasket was first developed by Flexitallic in the year 1912 to serve US refinery operations involving severe temperature and pressure fluctuations.

Spiral wound gaskets are used for
High-Temperature service applications.
High-pressure applications.
Corrosive fluids.
Flammable Fluids.
Hydrogen, etc.

Construction of Spiral Wound Gaskets
A spiral wound gasket is a semi-metallic gasket. It consists of a spirally wound v-shaped metallic with a non-metallic filler material. There are three elements that constitute a spiral wound gasket. They are:
Outer ring: Also known as a guide ring or centering ring, the outer ring of a spiral wound gasket is usually made of carbon steel material. The main purpose of this element is to center the gasket while inserting it into a bolted flange joint.
Inner ring: The inner ring is one of the most important parts of a spiral wound gasket as it prevents windings from buckling inside the pipe. In the situations of buckling of a gasket, parts of it get sucked into the pipe and eventually flow through the piping system to get caught/wrapped on something. Inner rings prevent this phenomenon and help in avoiding the problem.
Sealing element: This is the element of the spiral wound gasket that creates a tight seal to prevent leaks. The sealing element encompasses both windings and filler material. In general, spiral wound gaskets use a flexible graphite filler material rated for high temperatures. The graphite as filler material also helps the gasket to avoid flange distortion and joint misalignment. Another common filler material is PTFE (Polytetrafluoroethylene). However, PTFE is not suitable for use in high-temperature applications. The most widely used winding materials are Stainless Steel and Monel.

Refer to Fig. 1, which clearly shows these three elements of a spiral wound gasket.

Markings on Spiral Wound Gasket
Spiral wound gaskets are identified using different markings on the gasket. Each marking provides brief information about the spiral wound gasket specification important during the gasket selection process.
Some of the necessary information that the markings on the spiral wound gasket provide are:
Design Standard or Code: The code based on which the spiral wound gasket is designed and manufactured is clearly marked. In Fig. 1, you can easily find the standard ASME B16.20.
Name of the Spiral Wound Gasket Manufacturer: One can easily understand the manufacturer of the gasket by looking at the manufacturer name mentioned on the gasket.
Winding and Filler Material: Both the winding and filler materials are clearly specified on the spiral wound gasket. Specific gasket colors also provide a lot of information regarding the materials.
Diameter and Pressure class: The size of the gasket and the load the spiral wound gasket can handle, are specified by the Diameter and Pressure Class marking on the gasket. The usual pressure classes for spiral wound gaskets are 150, 300, 400, 600, 900, 1500, and 2500. With an increase in pressure class, the ability of the spiral wound gasket to withstand pressure increases.
Inner and Outer ring material

Materials for Spiral Wound Gaskets
The usual materials that are used in a spiral wound gasket are provided in table-1 below:

Metal Winding Strip MaterialFiller MaterialGuide Ring Material
Stainless Steel Grade 304GraphiteStainless Steel Grade 304
Stainless Steel Grade 304LPTFEStainless Steel Grade 316L
Stainless Steel Grade 316LCeramicStainless Steel Grade 316Ti
Stainless Steel Grade 316TiNon-sintered PTFEStainless Steel Grade 321
Stainless Steel Grade 310Non-Asbestos FiberStainless Steel Grade 347
Stainless Steel Grade 321AluminumStainless Steel Grade 410
Stainless Steel Grade 347Treated Asbestos FiberMonel 400
Stainless Steel Grade 430 Nickel 200
Stainless Steel Grade 317L Alloy 20
Alloy 20 Titanium
Monel 400 Hastelloy B2
Titanium Hastelloy C276
Nickel 200 Incoloy 800
Inconel 600 Incoloy 825
Inconel 625 Inconel 600
Inconel X-750 Carbon Steel
Hastelloy B2  
Hastelloy C276  
Incoloy 800  
Incoloy 825  
Duplex Stainless Steel  
Tantalum  
Zirconium  

Table 1: Spiral Wound Gasket Materials

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Categories: Technical Information

Both spiral-wound as well as kammprofile (derived from the German word ”Kamm”=comb) or grooved gaskets are used in various applications such as refineries, petrochemical plants, powert plants etc. Over the past few years, the use of kammprofile gaskets have seemed to gain momentum over the conventional spiral-wound gaskets, since they tend to provide tighter sealing and increased service life.

Spiral-wound gaskets
They basically consist of alternating plies of compressible filler material and a metallic strip (winding) wrapped in a way similar to the grooves of a phonograph record. The most common method for centering this type of gasket is through the use of a metal outer ring. Besides serving the role of centering the gasket, this metal outer ring also limits the gasket’s compression. Once the gasket is installed, the filler material is pushed between the plies, thus creating a seal between the flange mating surfaces, also covering any imperfections.

Initially, a common filler material used in gaskets was asbestos. However, due to health-related issues, use of asbestos is no longer allowed and other materials like rubber, PTFE, graphite etc have replaced use of asbestos nowadays.

Spiral-wound gasket dimensions and sizes for ASME B16.5 (flanges up to 24 inches nominal size) and ASME B16.47 flanges (flanges with a nominal size equal or bigger than 26 inches) are stipulated in ASME B16.20 standard (”Metallic gaskets for Pipe Flanges”).

Spiral-wound gaskets present some disadvantages:

  • They are very susceptibe to damage and prone to ”springing” when dropped, bumped or not properly handled.
  • Large size gaskets tend to be very dificult to handle, since their windings have a tendency of coming out.
  • Quite often, it may be necessary to equip them with inner rings as well. If inner rings are not supplied, then the windings run the risk of buckling, thus considerably reducing the load that can be safely imposed and maintained on them. Adding an inner ring gives an additional compression limiting stop and provides a heat and corrosion barrier protecting gasket windings and preventing flange erosion. It is usual to select inner ring material to be the same as the metal winding.

Kammprofile gaskets
Kammprofile gaskets were first developed in Germany and following DIN 2697 standard approximately 40 years ago. They consist of a solid metal core with concentric serrations and faced with a non-metallic material like graphite, various types of PTFE etc.

Once the gasket is installed, the soft non-metallic material is forced into the metal core serrated grooves. As a result, as the compressive stress increases, multiple concentric high-pressure seals are created along the gasket face surface.

Brief comparison

Unlike a spiral-wound gasket, all of the compressive force is exerted on the kammprofile graphite facing, thuse resulting in a very tight seal. Since the kammprofile is basically solid metal, as opposed to alternating plies of metal and filler applied at spiral-wound gaskets, it is extremely resilient and easy to handle even in large diameters.
Kammprofile gaskets compress significantly less than spiral-wound gaskets, approximately in the order of 0.022 inches in comparison to average 0.050 inches for spiral-wound gaskets. As a result, kammprofile gaskets load more quickly with reduced risk of non-parallel flanges.

Price-wise, kammprofile gaskets are significantly more expensive. However, their increased upfront costs can be compensated by avoiding costly, unscheduled outages and loss of production.

Spiral-wound gaskets may have a small advantage in case the mating flanges are too close and if the gasket is expected to be susceptible to mechanical damage or abuse during installation, since the graphite facing is more vulnerable to mechanical damage. Likewise, in some occasions, spiral-wound gaskets may be more resistant to oxidation, since the windings keep the graphite in place and protect it.

On the other hand, kammprofile gaskets are more tolerant to sealing surface defects and seal more effectively in fugitive emissions services.

Summing up, although there appears to be a shift towards the use of kammprofile years in the last years, the choice is not always clear and could finally come down to personal preference.
In any case, when properly manufactured and installed, both gasket types provide reliable seal arrangements.

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