Abstract: This invention relates to a high pressure valve of the dump type. The valve body contains a slideable, hollow spool with ports connecting its interior and exterior. When the valve is in the on position, all ports are located in the pressurized portion of the valve body, and fluid flows to an outlet connected to the hollow spool. In the off position, at least one port is outside the pressurized area of the valve body, thereby relieving fluid pressure. The ports slide through a seal of self-pressurizing construction. The valve may also be used as a high pressure swivel, or combination valve swivel, by rotating the spool, if the spool is supported by bearings.