A method of quantifying the capacity of a metal-to-metal seal between tubular components, comprising:
- providing a fixture, comprising:
- a first tubular component carrying a first metal seal surface and having a male connection;
- a second tubular component carrying a second metal seal surface and having a female connection;
- the first metal seal surface and the second metal seal surface being brought into contact by an engagement of the male connection of the first tubular component and the female connection of the second tubular component to form the metal-to-metal seal, the metal-to-metal seal having a contact load that acts in an interfacial region between the first metal seal surface and the second metal seal surface;
- a contact stress regulator to control the contact load acting between the first tubular component and the second tubular component to alter the contact load in a predictable manner;
- an inlet passage being provided to communicate a test fluid to an inlet side of the metal-to-metal seal and an outlet passage on an outlet side of the metal-to-metal seal;
- and
- one or more sensors for measuring the pressure differential between the inlet side and the outlet side of the metal-to-metal seal in isolation from any prior or sequential seals through which the test fluid may tend to pass including those that may form part of the engagement between the male connection of the first tubular component and the female connection of the second tubular component;
- engaging the male connection of the first tubular component and the female connection of the second tubular component to bring the first metal seal surface and the second metal seal surface into contact;
- controlling the contact load acting between the first tubular component and the second tubular component;
- directing the test fluid under pressure through the inlet passage to the inlet side of the metal-to-metal seal to apply a pressure differential across the metal-to-metal seal;
- monitoring for the onset of leakage at the outlet passage while inducing sufficient pressure to just cause the onset of leakage and determining a measure of the contact load acting between the first metal seal surface and the second metal seal surface;
- and
- calculating a measure of a capacity of the metal-to-metal seal as the pressure differential across the metal-to-metal seal just induces leakage as the contact load acting between the first seal surface and the second seal surface of the metal-to-metal seal is reduced.