A high integrity protection system (HIPS) for protection of a pipe downstream of a wellhead includes an inlet connected to the wellhead; outlet connected to the downstream pipe; two sets of two series-connected surface safety valves (SSVs) in fluid communication with the inlet and outlet, the sets being in parallel fluid flow relation to each other, either one or both of the sets of SSVs operable as a flowpath for fluids entering the inlet and passing through the outlet to the downstream pipe; two vent control valves (VCVs), each connected to piping intermediate one set of series-connected SSVs, the VCVs being in fluid communication with a vent line, whereby, upon opening of a VCV, process pressure between the two SSVs is vented; a signal-generating safety logic solver, in accordance with preprogrammed safety and operational protocols; and pressure sensing transmitters attached to piping upstream of the HIPS outlet.