A peep sight is a small round or oval disc with a hole in the middle. It is placed between the strands of the bowstring at eye level. A peep sight acts a rear sight, precisely aligning the bowstring and target. Slighting is more precise when two locations between the archer's eye and the bull's-eye aligned than when just one is aligned. It can improve aiming accuracy.

Petroleum engineering is engaged in the exploration and production activities of petroleum as an upstream end of the energy sector. It covers a wide range of topics, including geology, geochemistry, geomechanics, geophysics, oil drilling, geopolitics, seismology, tectonics, thermodynamics, well logging, well completion, oil and gas production, reservoir development, and pipelines.

Pilot control regulator is a two-path control system. The main valve diaphragm responds quickly to downstream pressure changes, causing an immediate correction in the main valve plug position. The pilot diaphragm responds simultaneously, diverting some of the reduced inlet pressure to the other side of the main valve diaphragm to control the final positioning of the main valve plug.

Pilot torch is an atmospheric pilot with a soft, stable flame designed to operate on low-pressure gasses. The basic components are the AN tip, SPI inspirator, a length of mixing tube and a control valve. This is used to ignite the oil from the main oil guns. It is used when placing a main oil gun in or taking a main gun out of service and to assist in burning any oil scavenged from the main oil gun during the steam purge cycle.

Pilots are used on atmospheric burners and are available for various types of gases. It can be provided with pet cock and mounting bracket, or with thermocouple or with spark electrode. These are available in many different types and styles.

Pipe burners are widely used atmospheric gas burners made in many sizes, lengths, and capacities. These are designed with correctly spaced ports properly sized for the gas to be burned. These burners are used for the heating of vats, kettles, tanks and other containers which permit the burners to be installed underneath. These are also used for oven and furnace heating for many applications where materials may be heated by direct contact.

Pipeline integrity testing is carried out by filling the line with water and pressuring it to specified levels for a period of time. One by-product of this type of test is a huge volume of water, which is usually contaminated with organic materials. Another common form of pipeline integrity testing is known as intelligent pigging. A pig is a tool which is pumped through the pipeline for several purposes including to insure it is unobstructed & open, to perform maintenance tasks on the interior of the line or to conduct sophisticated monitoring procedures that identify to the client if an abnormality exists anywhere along the line's length.

Piping and instrumentation diagrams are used to guide detailed design and construction of process plants. These diagrams are suitable for interconnection of process equipment and the instrumentation used to control the process.