What are M & Y values?

"What are M & Y Values?"

At Corseal, we often receive inquiries about the M & Y values associated with our gaskets. These values are crucial for customers who are designing flange joints in accordance with the ASME Boiler and Pressure Vessel Code. Understanding these values is essential for ensuring the integrity and safety of pressure vessels and piping systems.

In layman's terms, the design of a flange is critical to achieving an adequate compression load on the gasket's contact area, which is typically measured in terms of stress, such as pounds per square inch (psi). This compression is necessary to create an effective initial seal. The gasket must be capable of conforming to the surface of the flange, including any serrations that might be present, and must be compressed sufficiently to close off any internal voids or gaps that could lead to leaks. This compression stress is fundamentally what the "Y" value represents. It is a measure of the minimum seating stress required to achieve an initial seal.

On the other hand, the "M" value is a critical parameter that allows the flange designer to ascertain the compression load necessary to maintain the seal when the vessel is under pressure. This involves ensuring that the flange assembly has adequate strength and bolting to keep the joint intact against the hydrostatic end force. Additionally, it must apply an additional "net stress" on the gasket. The "M" value functions as a multiplier or a maintenance factor, which helps in determining the additional stress required. When designing, the flange and bolting must be capable of holding the flanges together under pressure—countering the hydrostatic end force—and exerting an additional stress on the gasket equivalent to "M" multiplied by the internal pressure. 

The design process involves two critical calculations: one to determine the load necessary to seat the gasket, which relates to the "Y" value, and another using the "M" value along with the specified internal pressure. Ultimately, the flanges are constructed based on the larger of these calculated values to ensure safety and functionality. This approach ensures that the flange design is robust, capable of handling the operational pressures, and maintains the integrity of the seal throughout the vessel's service life.

See below for SPIRAL WOUND & CAMPROFILE GASKETS values.

What are the M and Y values for Kammpro(Camprofile), CMG, CMGT, CMGPTFE, Spiral Wound Gaskets (W, WR, WRI), and WRI-LC?

What is the yield strength for B7 bolts?

105 KSI

How can torque value be calculated?

T = (S * D * A * R) / 12

Where:

• T: torque value (ft-lb)
• S: required bolt stress (PSI)
• D: bolt diameter (in)
• A: area at root of thread (square inches)
• R: friction factor