Pipefitter Blueprint Reading and Symbols 5 — Questions and Answers
Question 1: What is the primary purpose of a 'north arrow' symbol found on a piping plan drawing?
- To indicate magnetic interference near instrumentation
- To orient the drawing relative to true or plant north for field layout (Correct answer)
- To show the direction of flow in the main header
- To identify the highest pressure zone on the drawing
Correct answer: To orient the drawing relative to true or plant north for field layout
The north arrow orients the piping plan to plant north (or true north), allowing field crews to align the drawing with the actual site.
Question 2: On a piping drawing, what does the symbol 'FW' or a small flag on a weld symbol indicate?
- A field weld to be made during construction rather than in the shop (Correct answer)
- A full-penetration weld required on both sides
- A fillet weld with a specific throat size
- A weld that requires post-weld heat treatment
Correct answer: A field weld to be made during construction rather than in the shop
A field weld flag (small flag on the weld symbol tail) indicates the weld is to be made at the job site, not prefabricated in the shop.
Question 3: A piping drawing shows a reducer symbol labeled '8" x 6" ECC RED'. What does 'ECC' tell a pipefitter?
- The reducer is eccentric, meaning the centerlines of the two ends are offset (Correct answer)
- The reducer has an extra-heavy wall schedule
- The reducer is used only in eccentric (vertical) service
- The reducer has eccentric bolt-hole patterns
Correct answer: The reducer is eccentric, meaning the centerlines of the two ends are offset
ECC (eccentric) means the reducer has offset centerlines, used to maintain a flat bottom-of-pipe for drainage or flat top-of-pipe to avoid air pockets.
Question 4: Which symbol on a P&ID represents a pneumatically actuated control valve?
- A diamond shape with a circle on top
- A bow-tie (two triangles point-to-point) with a diaphragm actuator symbol above (Correct answer)
- A rectangle with crossed diagonal lines
- A circle with an 'A' inside connected to the valve stem
Correct answer: A bow-tie (two triangles point-to-point) with a diaphragm actuator symbol above
A pneumatically actuated control valve is shown as a bow-tie valve body symbol with a diaphragm (dome) actuator symbol on top per ISA 5.1 standards.
Question 5: On an orthographic piping drawing, what does a circle with a horizontal line through the center, drawn on a pipe, typically indicate?
- A spectacle blind in the open position
- A pipe cap
- A union fitting (Correct answer)
- A pipe nipple close
Correct answer: A union fitting
A circle bisected by the pipe centerline is the standard symbol for a union, indicating a mechanical joint that allows the pipe to be disconnected without cutting.
Question 6: What does the callout 'CONT. SUPP. @ 10'-0" O.C.' on a piping drawing mean for a pipefitter?
- Install a continuous support every 10 feet on center along the pipe run (Correct answer)
- The pipe has a continuous slope of 10 feet over its entire run
- Install one support at the 10-foot mark from the pipe origin
- The support must carry a continuous load of 10 feet of pipe weight
Correct answer: Install a continuous support every 10 feet on center along the pipe run
'CONT. SUPP. @ 10'-0" O.C.' means continuous supports spaced at 10-foot intervals on center along the entire pipe run.
Question 7: On a piping isometric, a small square drawn perpendicular to the pipe with 'PG' labeled indicates:
- A pipe guide (lateral restraint only, allows axial movement)
- A permanent ground anchor fixed in all directions
- A pressure gauge connection or tapping point (Correct answer)
- A pipe grip clamp for seismic support
Correct answer: A pressure gauge connection or tapping point
A square tapping symbol labeled 'PG' on an isometric denotes a pressure gauge connection or instrument tap location on the pipe.
Pipefitter Blueprint Reading and Symbols 5
What is the primary purpose of a 'north arrow' symbol found on a piping plan drawing?