The design rules for clamped connections are described in Appendix 24 of ASME VIII, Division 1. While tedious in nature, these rules will permit you to perform custom designs as needed. Unfortunately, some of the data (such as seal retaining loads, seal make-up loads, seal gasket diameter, clamp geometry, etc. are considered proprietary information and the suppliers are very reluctant to provide it. A more practical approach maybe to provide the design conditions to a vendor and let them perform the design calculations for you. Vendors you can contact include:
LTS Energy -
