Starting and stopping frac pumps

A method comprising:

• starting a frac pump;
• routing, inside the frac pump, flow of a fluid discharged from the frac pump into a first tubular that feeds the fluid back into the frac pump;
• routing, after the frac pump has reached an operating condition, the fluid discharged from the frac pump into a second tubular that has higher pressure than the first tubular;
• pumping the fluid into the second tubular;
• routing, after the pumping, flow of the fluid discharged from the frac pump into the first tubular that feeds the fluid into the frac pump;
• shutting down the frac pump;
• and
• releasing, while shutting down the frac pump or subsequent to shutting down the frac pump, pressure from the first tubular via a pressure relief valve.

A system comprising:

• a first tubular fluidically connected with one or more frac pumps and one or more first flow control devices that are fluidically connected to a second tubular that is fluidically connected to a wellhead, wherein the first tubular and the second tubular define a first flow path for transporting fluid to the wellhead;
• and
• a third tubular fluidically connected with the first tubular and one or more second flow control devices that are fluidically connected with a fourth tubular, wherein the third tubular and the fourth tubular define a second flow path for transporting fluid to a location other than the wellhead and wherein the one or more second flow control devices comprise a valve and a choke,
• wherein during a start-up process for the frac pumps, at least one of the first flow control devices is configured to be closed and the second flow control devices are configured to be open, wherein the choke is configured to produce fluid pressure in the first tubular that exceeds fluid pressure in the second tubular during well operations.

A system comprising:

• a first tubular fluidically connected with one or more frac pumps and one or more first flow control devices that are fluidically connected to a second tubular that is fluidically connected to a wellhead, wherein the first tubular and the second tubular define a first flow path for transporting fluid to the wellhead;
• and
• a third tubular fluidically connected with the first tubular and one or more second flow control devices that are fluidically connected with a fourth tubular, wherein the third tubular and the fourth tubular define a second flow path for transporting fluid to a location other than the wellhead and wherein the one or more second flow control devices comprise a valve and a choke,
• wherein, during a shutdown process for the frac pumps, at least one of the first flow control devices is configured to be closed and the second flow control devices are configured to be open, wherein the second flow control devices being open causes fluid pressure in the first tubular to decrease.