Tag
#piping
40 topics across all disciplines.
Pipe materials — what the grade on the spec actually means
A106, A312, P11 — how to read a piping material grade, why carbon steel is the default, and what forces an upgrade to alloy or stainless.
Pipe sizes and schedules — why NPS 2 is not 2 inches
NPS, DN and schedule numbers explained. Why the outside diameter is fixed, what changes when the schedule goes up, and how to read a pipe size chart.
Line sizing — why pipe diameter is an economic decision
The two criteria that size every line, why a bigger pipe costs once and a smaller one costs forever, and the lines where neither rule applies.
Fittings and branch connections — how a pipe changes direction
Elbows, tees, reducers and caps, and the branch fittings that take a small line off a big one. What each is for, why the dimensions are fixed, and why a branch needs reinforcement.
Valve types — picking one for the duty, not the drawing
Gate, globe, ball, butterfly and check valves explained by what each is built to do. Why throttling with a gate valve destroys it, what double block and bleed means, and how check valves slam.
Flanges and pressure classes — why Class 150 is not 150 psi
What a flange class means, how pressure–temperature ratings work, the common facing types, and why a gasket and bolt set are part of the rating.
Gaskets and bolting — why most flange leaks are assembly, not hardware
How a bolted joint actually seals, reading a spiral wound gasket by its colours, choosing stud and nut materials, and the bolt-up sequence that decides whether any of it works.
Reading a line class — the document that has already decided
How a piping material specification works, how to decode a line number, what a spec break is, and why almost every piping decision on a project was made before you arrived.
Pipe supports and thermal expansion — why you cannot just bolt it down
Hot pipe grows, and it grows with enormous force. How expansion is calculated, why loops exist, what anchors, guides and spring hangers actually do, and how supports protect equipment nozzles.
Expansion loops and offsets — sizing the detour that absorbs the growth
How a loop actually absorbs movement, the guided cantilever hand calculation that gives you a first size, why the answer never fits the rack, and the honest ranking of what to do when it does not.
Expansion joints and bellows — pressure thrust and why they are the last resort
What a bellows can and cannot absorb, the pressure thrust that dwarfs the thermal force it was fitted to relieve, tied and hinged and gimbal arrangements, guide spacing, cycle life, and the installation errors that kill them early.
Anchors, guides and restraint schemes — deciding where the pipe may move
A restraint scheme is one decision for a whole run, not a scatter of supports. Where an anchor belongs, what it actually carries once friction is counted, line stops against full anchors, the gap that is the design, and the accidental anchors that site creates.
Pipe support standards and details — reading SP-58, SP-69 and a project detail sheet
What the support standards actually fix, why a project standard detail is a specification rather than a catalogue, the welded attachment problem on alloy and sour service, shoes and trunnions and shields, and what goes wrong when a support is left to the field.
Spring hanger selection — variable, constant, and the pin nobody pulled
Choosing a spring for a line that moves vertically. Hot and cold load, the load variation limit and when it forces a constant effort unit, travel and rod swing, why the pointer is the most useful thing on a walkdown, and the installation errors that make a spring worse than no spring.
Nozzle loads and allowables — the constraint that really governs hot piping
Why machine nozzle allowables are so small, where they come from for pumps, compressors, turbines and vessels, what exceeding them actually does, why the symptom surfaces in somebody else's report, and the design and field rules that prevent it.
Pump piping layout — the suction side is where the decisions are made
NPSH available as a consequence of layout rather than a number handed to you. Eccentric reducers and the pocket they prevent, straight run before the impeller, the elbow that must not be in the shaft plane, parallel pump symmetry, strainers, minimum flow, and the discharge order.
Plot plan and equipment spacing — the drawing everything else inherits
What actually sets the distance between equipment, the four drivers that pull against each other, the pipe rack as the spine and how its tiers are allocated, prevailing wind and fired equipment, roads and containment, and why a plot plan mistake cannot be recovered downstream.
Access, operability and maintenance space — what the plant is judged on afterwards
Valve reach and stem orientation, why a chain operator is a confession, platforms and the dead-end with one ladder, headroom, bundle pull and rotor withdrawal, drop-out areas and davits, and the model review that is the last chance to find any of it.
Relief valve and flare piping — the 3 per cent rule, backpressure and reaction force
The piping engineer's half of overpressure protection. Why a relief valve inlet must be short and generous, what chatter actually is, built-up and superimposed backpressure and the 10 per cent limit, reaction force on an open discharge, flare header slope, and the car-sealed valve that must never be closed.
Reading a WPS and a PQR — what is on the sheet and what the tests proved
The practical document skill — what each field on a welding procedure specification is for, what a qualification record actually recorded, and what tensile, bend, impact, macro and hardness results each demonstrate about the joint.
Section IX essential variables — what invalidates a procedure qualification
Why a WPS can be revised freely in some respects and requalified from scratch in others. Essential, non-essential and supplementary essential variables, the ranges a PQR actually qualifies, and the low-temperature trap that turns a harmless change into a requalification.
Welder qualification and continuity — the ranges a ticket covers, and the register nobody updates
What a welder performance qualification actually establishes, the ranges it carries in thickness, diameter, position and process, how continuity lapses at six months, and why the expired ticket is always found after the weld is made.
Joint preparation and fit-up — the hold point you only get once
Bevels and root gaps, internal misalignment and the limits on it, why trimming or counterboring is allowed where grinding the bore is not, tack welds as part of the final weld, and what an inspector checks in the minutes before the root goes in.
Preheat and post-weld heat treatment — hydrogen, hardness, and reading the chart
What preheat is actually for, why interpass temperature has a ceiling as well as a floor, when PWHT is required and when it may be exempted, how to read a chart recorder trace against the specified cycle, and the hardness survey that decides it in sour service.
Examination extent and progressive sampling — what five per cent actually obliges
How fluid service sets the amount of examination, why the sample has to represent each welder on each procedure, and the progressive sampling rule that turns one rejected weld into a widening scope — the part of Chapter VI taught almost nowhere.
Inspection and test plans — hold, witness, review, and who signs
What an ITP actually is, how it is built line by line from the code and the specification, what each of the four intervention levels obliges, why a document full of hold points is worse than a short one, and the notification failure that turns a witness point into nothing.
Non-conformance and corrective action — the four dispositions, and why NCRs repeat
Writing an NCR somebody can act on, the difference between rework, repair, use-as-is and reject, who may grant a concession, and why closing non-conformances one at a time without ever raising a corrective action guarantees the same defect next week.
Inspector competence and certification — who may interpret, and who only operates
SNT-TC-1A as an employer's written practice rather than a certificate, ISO 9712 as the independent route, what Levels I, II and III may each do, and why the inspector's own qualification is the first thing a client audits.
Erection sequence and constructability — why the isometric order is not the build order
Why the number on an isometric says nothing about what has to be built first, how access is lost and regained, the dependencies that decide a piping sequence, and the habit of working backwards from the date that cannot move rather than forwards from today.
Spool handling and temporary support — the hours between landed and supported
The period in which a spool has been released by the crane but does not yet have the supports it was designed to have, why that state has no design behind it, what has to be established before the hook comes off, and why Friday afternoon is when pipe ends up on the floor.
Lift plans and rigging basics — sling angle, centre of gravity, and the reasons to stop
What a lift plan has to state before anybody touches a spool, why the tension in a sling leg is not the load divided by the number of legs, how an offset centre of gravity behaves, and the short list of conditions under which a supervisor stops a lift regardless of who is waiting.
Scaffold access and handover tags — access as a scheduled resource
Why access is a resource with dates rather than a condition of the site, what a scaffold tag actually certifies and what it does not permit, why an untagged scaffold is a red one, and the load class that stacking materials quietly exceeds.
Pressure test packs and reinstatement — the gate, and what gets put back afterwards
What a test pack contains and why it is built as the work proceeds, the procedure and the calibrated gauge, the falling pressure that is temperature rather than a leak, and the reinstatement register that is what actually keeps a tested system honest.
Tie-ins and shutdown windows — preparing for the hours that cannot be extended
Why a tie-in window is the only genuinely fixed date on a project, what must be complete before it opens, why a trial fit is the highest-value hour on the job, what actually causes a window to overrun, and how to decide in advance what will be cut if it slips.
Diameter-inch and progress measurement — the unit piping is paid in
What a diameter-inch is and how it is counted, why it under-represents small bore, the difference between claimed and earned progress, the measurement rule that has to be agreed before work starts, and why the last ten per cent of a piping package takes months.
Construction productivity factors — why the same weld takes three times as long
Why a norm measured in the shop does not survive contact with a live unit, the conditions that multiply the hours without changing the work, crew composition and what a waiting welder costs, and the difference between a crew that is busy and a crew that is producing.
Supervising under a permit — the shift you signed for
Not what a permit is, which is covered elsewhere and free, but what changes when you are the person who signed it — what to verify at the work rather than on the form, the conditions routinely accepted and not met, why a gas test expires, and what handing back actually requires.
Site records and the daily diary — writing for somebody who will not believe you
Why the site diary is the most valuable document a supervisor produces, what distinguishes an entry that is evidence from one that is worthless, what to record every day regardless, and why contemporaneous matters more than detailed.
Variations, backcharges and notice — the difference between noticing and notifying
How to recognise an instruction that is really a variation, why the entitlement usually depends on the notice rather than the change, what a backcharge is and how it runs in both directions, and the one-sentence note that protects a position without starting an argument.
Insulation, tracing and coatings — the layers outside the pipe
Four different reasons to insulate and why confusing them causes corrosion, how steam and electric tracing differ, why tracing fails silently, and why surface preparation is most of a paint system.