Often Great Lakes Wellhead gets asked, “Which seal is best for my Wellhead?” Here is what we think!
The deciding factors for determining which seal should be used in your wellhead should be based on temperature, environmental conditions, and cost.
Temperature is the most common deciding factor for determining which seal is best to use. Factors to consider when determining temperature include atmospheric temperature, formation or fluid temperature and welding temperature (Preheat and Post weld heat). The following table shows the temperature ranges of various seal elastomers commonly used in API 6A wellheads.
Figure 1: Temperature Rating Chart for common elastomers used in seals
Environmental conditions will also determine which seat compound to use. For the oil and gas industry, factors to consider include: H2S, Chemical treatments, particulates (debris, sand, salt), the velocity of fluids, CO2, Ozone or Sunlight, Fungus or Mold, and oxidation.
Common seals used in our industry are BUNA (NBR or Nitrile Rubber), VITON (Fluorocarbon, FKM or FPM), or HSN (Highly Saturated Nitrite or HNBR).
All provide excellent compression set resistance and both are designed to resist most oils and lubricants, especially petroleum-based lubricants.
BUNA (NBR or Nitrile Rubber)
VITON (Fluorocarbon, FKM, or FPM)
HSN (Highly Saturated Nitrite or HNBR)
All of these seals provide good to excellent resistance to the common chemicals used in the oil and natural gas industry. Some of the more exotic chemical treatments may present an issue and should be examined on a case-by-case basis. A good resource for reviewing the compatibility of specific chemicals can be found here: https://www.coleparmer.com/Chemical-Resistance
This is to be used as a guideline and if specific conditions in your operations is present feel free to reach out to Great Lakes Wellhead and we can determine a plan of action that will meet all of your project needs. Email us at Sales@glwinc.us