Sealing high pressure flow devices

A fluid end assembly, comprising:

• a housing having an external surface and an internal chamber;
• a first conduit formed in the housing and having first and second sections, each section independently interconnecting the internal chamber and the external surface;
• a second conduit formed in the housing, intersecting the first conduit and having third and fourth sections, each section independently interconnecting the internal chamber and the external surface;
• an endless groove formed in the housing such that the groove surrounds the third section;
• a tubular sleeve installed within the third section, in which the sleeve has a rear surface and a front surface and includes a cylindrical rear portion joined to a cylindrical front portion, in which the rear portion has a first outer surface having constant outer diameter and a first inner surface having a constant inner diameter, in which the front portion has a second outer surface having a constant outer diameter and a second inner surface having a constant inner diameter, and in which the constant outer diameter of the rear portion is larger than the constant outer diameter of the front portion and a maximum diameter of the groove;
• a seal positioned within the groove and engaged with the front portion of the sleeve proximate the front surface of the sleeve;
• a plurality of packing seals installed within the rear portion of the sleeve and engaged with the first inner surface of the rear portion;
• a retainer attached to the housing and engaged with the rear surface of the sleeve and configured to secure the sleeve within the third section;
• and
• a reciprocating plunger disposed at least partially within the sleeve and the plurality of packing seals.