ABSTRACT. Nubbins are predominately machined into a heat exchanger flange to create a high stress point to produce a tighter seal. Traditionally the gasket used when a nubbin is present is a Double Metal Jacket (DMJ), which consists of a metal jacket with a soft internal sealing material e.g. Graphite, PTFE.

The most commonly used thicknesses for Standard Flange gaskets are 1/16″ and 1/8″.

To measure such circle measure from the center of one bolt directly across to the center of the other bolt. The Outside Diameter is the measurement of the outside of the Flange or Gasket. The Inside Diameter is the measurement of the inside of the hole of a Flange or Gasket.

Use a ruler or measuring tape to find the diameter of your nipple (the horizontal width across it) in millimeters (1 cm = 10mm). Measure the nipple alone, do not include the areola, which is the outer edge around your nipple. Add 4 mm to this measurement, so if your nipple is 20 mm across, your flange size is 24 mm.

1) Gasket type. Solid metal gaskets (seldom used now) generally require nubbins in order to properly seat the gasket. 2) Cost. Per Appendix 2 of ASME Section VIII Div. 1, machining a nubbin onto the flange gasket surface usually reduces the required bolting area so that fewer (or smaller diameter) bolts can be used.

Gaskets calculates the dimensions and properties of flange gaskets such as; RTJ, BX, RX, CAF, etc. Gaskets are required to contain fluid under pressure and, it is hoped, that gasket compression does not damage the flange mating surfaces.

We have used something like a nubbin, but it’s more of a triangular profile rather than rectangular, for metallic ultra-high vacuum seals. Based on what I’ve read, ultra vacuum might be one of the few exceptions to the rule. I can do absolutely anything. I’m an expert! 1) Gasket type.

The flange gaskets calculator is a dimensional database and calculator, it does not include the calculation factors or material properties (‘m’ & ‘y’) that must be considered when designing/selecting the flange that will use them. The above data must be entered manually in the flanges calculator.