Datum Pipe 0.2.0

The milestone that closes the second stage: nonlinear supports, occasional loads, spring hangers and import (0.1.5–0.1.11), reviewed. No new features.

Fixes from an independent review of the engine.

• Two one-way or gapped supports touching on the same direction at one node now share its load equally, with a warning; each reported the whole load, so the equilibrium check failed.
• A bend whose radius is half its pipe's diameter or less is refused (its bend factor turned negative and the wall check passed); the wall check of such a bend fails.
• A spring hanger whose attachment moves in operating case 1 is sized on the pipe's movement relative to the attachment, so it carries its hot load in operation.
• Importing a piping component file joins an olet's branch to its run pipe (the run was not split there, leaving the branch unconnected).

Each with a regression test. The verification record (48 checks), the screenshots, the README and the site describe everything up to this release.

Datum Pipe 0.1.11

Import of piping component files.

Import. File › Export › Import a piping component file opens a plain-text .pcf file from a design tool as a new model:

• pipes; elbows and bends at their corner, with the radius from their tangent length; tees and olets; concentric and eccentric reducers (as concentric); valves, flanges and other in-line items as rigid parts with their weight;
• supports as one-way rests, or anchors, guides and line stops when their name says so;
• millimetres or inches; coordinates turned from Z up to Datum Pipe's Y up;
• pipes at the library's nominal sizes with Std wall, and the default material and line conditions: set them for the line.

Anything it cannot read is listed when the model opens. A sample file is in docs/examples/6-P-101.pcf.

Roadmap. The public piping benchmark problems published by nuclear regulators are dynamic problems (natural frequencies and response spectra), so they move to 0.4 with dynamics, where they can be checked. The next release is 0.2.0, which closes this stage.

Datum Pipe 0.1.10

Spring hanger selection.

Spring hangers. Supports › Spring Hanger puts a hanger on a node, and Analyze sizes it:

• the hot load H: the operating weight it carries with the pipe held level there;
• the travel Δ: its movement in operating case 1 with the hanger carrying H;
• the spring: the first size in the spring table whose working range takes both H and the cold load C = H + k Δ, with the load variation |k Δ| / H within the limit (25 % unless you change it).

Every load case is then solved with the chosen springs, each set to its cold load. A hanger no spring fits becomes a constant-force support carrying H, with a warning.

Spring table. Supports › Spring Table: the sizes hangers are chosen from, in order, with the load variation allowed. It starts with a generic table (three series with 25, 50 and 100 mm of working travel, twenty sizes each), not any maker's catalogue: replace it with your supplier's sizes.

Results. Results › Hangers lists each hanger's size, rate, hot load, travel, cold load, load variation and working range; the report has the same table.

Examples. The tank outlet's first support is a spring hanger sized by Analyze.

Verification. A new benchmark: a spring hanger on a heated riser and run, its hot load, travel, spring, cold load and load in operation by hand (48 checks).

Datum Pipe 0.1.9

Wind and static seismic loads, and the occasional stress check.

Wind. A design wind pressure, a shape factor Cd and the direction the wind blows, in the Inspector's Occasional loads (or Loads › Wind). Each element carries q × Cd × D per metre, with D over its insulation and cladding, from the part of the wind that blows across it: wind along a pipe puts no load on it.

Static seismic. Factors of g along X, Y and Z (Loads › Static Seismic); each element carries its operating weight per metre times them.

Load cases. With wind, OPE1+WIN (operating case 1 with the wind) and OCC WIN (the wind's own effect, OPE1+WIN − OPE1) are added; the same for seismic. The Load Cases dialog has an Occasional column for your own cases.

Occasional check. An occasional case's stress at each point is the sustained stress plus the stress of the occasional loads (the same expression, without pressure), against 1.33 Sh.

Your inputs. The wind pressure and the seismic factors come from the standards for the site; Datum Pipe reproduces none of their tables. Help › Sources lists the new equations.

Examples. The steam line on the rack has 0.8 kPa of wind from the south and 0.15 g of static seismic sideways.

Verification. Three new benchmarks: wind on a cantilever (tip deflection and root moment), static seismic on a cantilever (root force and moment), and the occasional stress at its root (43 checks).

Datum Pipe 0.1.8

Friction at rests and guides.

Friction. Rests, guides, line stops and restraints can have a friction coefficient μ (0.3 is typical for steel on steel, 0.1 for PTFE slide plates). It acts across the support's direction: a rest resists the pipe sliding horizontally, a guide resists it moving along the pipe.

Sticking and sliding. In each load case a support with friction holds the pipe while the force that needs is within μ × the load pressing the support; beyond that the pipe slides, and the support pushes back with exactly μ × its load against the movement, in whatever direction the pipe moves across it. A rest that lifts off has no friction. This is solved in the same iteration as one-way rests and gaps; sliding forces are found exactly from the support's own flexibility, one support after another, so supports at one node settle together.

Results. Support Loads shows each support with friction as sticking or sliding, with its friction force, which is part of the support's load and of the equilibrium check.

Examples. The steam line's rests and guides have μ = 0.3.

Verification. A new benchmark: friction at a heated rest, sliding (μ P, and the movement ε L − μ P L / EA) and sticking (E A ε) (38 checks).

Datum Pipe 0.1.7

One-way rests and gaps.

One-way rests. A rest can let the pipe lift off: it pushes the pipe up but never pulls it down. New rests are one-way; the Inspector switches it. Rests in files from earlier versions stay two-way, so their results do not change.

Gaps. Rests, guides, line stops and restraints can have a gap: below the pipe for a rest, on each side for the others. The support takes no load until the pipe has moved across it.

How it is solved. With one-way rests or gaps, each load case is solved again until every such support has settled as touching or open: a touching support must push the pipe, not pull it, and an open one must not be passed. The expansion range is still the difference of the operating and sustained results. If only open gaps hold the piping in some direction, they keep a light stiffness (1 N/mm) so the case can be solved, with a warning.

Results. Support Loads shows each one-way or gapped support as touching, open or lifted off, with the pipe's movement and the gap, and how many solves the case took.

Examples. The examples' rests are one-way, and the steam line's guides have 3 mm gaps.

Verification. Two new benchmarks: a one-way rest under a cantilever (lifting off when pushed up, carrying the load when pushed down) and a gap closing at a cantilever's tip (34 checks).

Datum Pipe 0.1.6

Windows now lists the publisher as Datum.

Datum Pipe 0.1.5

Code check fixes, and where every equation comes from.

Minimum wall.

• A bend is also checked at its intrados, where the wall needs most metal: the design thickness uses the bend factor I = (4R/D − 1)/(4R/D − 2).
• A pressure design thickness of D/6 or more now fails, with a warning: the thin-wall equation does not apply there.
• A reducer is checked at both ends, each with its own pipe (diameter, wall, corrosion and mill tolerance); it was checked at its large end only.

Tees. The branch of a tee uses the effective section modulus Ze = π r₂² Ts, with Ts the lesser of the run's wall and ii × the branch's wall. Analysis Settings can turn it off for code editions that use the branch pipe's own section modulus.

Pressure elongation. Straight pipe can grow with its pressure in the operating cases (ε = (σL − ν σh)/E). Off unless you choose it in Analysis Settings; the sustained case never includes it.

Shared supports. Two rigid supports holding the same direction at one node now share its load equally, with a warning; the first one took it all.

Sources. Help › Sources lists every equation with where it is published in the open engineering literature: Barlow and Lamé, the membrane theory of a torus, von Kármán, Clark and Reissner, Markl, Rodabaugh and George, and beam theory. The README, NOTICE and report say that Datum Pipe contains none of the code's text, tables or figures and is not affiliated with or endorsed by ASME.

Verification. Three new benchmarks: a bend's wall at its intrados, pressure elongation between two anchors, and a tee branch's effective section modulus (29 checks).

Datum Pipe 0.1.4

Polish: the build to start with. Every example analyzes, draws its isometric and prints its report.

Fixes from an independent review of the engine.

• An expansion range between two operating cases now takes the hot allowable Sh at the hotter of the two cases; it took the second case's even when the first was hotter, which was on the unsafe side.
• Guides and line stops at a tee act along the run; the branch was averaged into the pipe's direction, so a line stop could take loads across the pipe. At a corner, where there is no single direction, Datum Pipe now says so.
• A tee drawn as the end of its branch takes its stress intensification from the run pipe, and a tee without a straight run gets its plane from its legs (with a warning).
• Bends' stress intensification factors use the lowest operating pressure for the pressure correction (on the safe side in every case); their flexibility still uses the highest.
• A flexible anchor's stiffness applies to its three movements; its rotations are held.
• A reducer's small end uses its own pipe's corrosion allowance in the sustained stress.

Isometric. The sheet fills the window at the proportions of a landscape page, with its title block the same width.

Report. The title block's labels print in their boxes (they were pushed to the foot of the first page).

Results. Code stresses are listed in table order, element by element, with each bend after its straight part; Worst first still sorts them by ratio.

Examples. The turbine nozzle of the steam line points the right way (from the turbine into the pipe).

Checked. A final pass over every worked example: each one analyzes with its reactions balancing its loads, draws its isometric and prints a report of four to six pages. New screenshots for the README and the family site.

Datum Pipe 0.1.3

Editing tools, smoother typing in the table, and a tidier report and isometric.

Expansion loop wizard. Select a straight element and choose Model › Expansion Loop: give the loop's width and height, sideways or upwards, and the element becomes a loop in its middle with four long-radius bends, drawn to scale before you make it.

Copy and mirror a section. Model › Copy Section copies a range of table rows, with their components and supports, onto any node; Mirror Section does the same mirrored across X, Y or Z.

Typing in the table. Tab and Enter keep the keyboard in the table after every edit (before, an edit rebuilt the rows and the cursor was lost), and Enter in the last row adds the element and stays there for the next one.

Report and isometric. Report pages keep their content inside the header and footer, headings print in plain type, the isometric shows one stress ratio tag per element (bends showed two), and the 3D view fits the model more closely.

More checks. Hand-worked cases for the hydrotest (the line full of water) and for an occasional case (checked against 1.33 Sh).