19.2 General Industry Codes and Procedure Use

A General Industry codes item is a reading test dressed as an NDT question. The stem hands you a procedure fragment, a contract clause, or a short acceptance table and asks whether you know what each layer is allowed to decide. The method physics you already proved on the general paper is assumed. What is not assumed is that you can mark up a procedure the way a Level II marks it on the first job of a shift.

This section is the GI half of the specific-exam codes heading. Pressure Equipment uses a different book list and is the next section. The reading method is the same on both sectors: find scope, product form, essential variables, process control, lighting, and the acceptance pointer before you change anything.

How to read a procedure

Open the employer procedure — not the textbook chapter — and read it in this order. Skip around and you will magnetize a part that is outside scope or apply the wrong acceptance row.

1. Scope

Scope is the first gate. It states the method, the techniques that are qualified, the product forms (welds, wrought, castings, forgings, machined hardware), the thickness or size range, the materials (for example ferromagnetic alloys only), and the exclusions (coated parts, austenitic welds, hardware already painted, parts smaller than a named limit). If the part in the stem is a 60 mm forging and the procedure's scope stops at 50 mm, you do not "stretch" the procedure. You stop and elevate. Scope is not a suggestion.

Scope also names whether the procedure is for production, in-service, incoming, or final examination. A receiving-inspection PT procedure that excludes assembled hardware is the wrong document for a welded frame that already has fasteners installed.

2. Product form

Product form decides access, discontinuity family, and often the calibration piece. A weld procedure may require scanning both sides of the cap and the heat-affected zone. A casting procedure may require extra attention to gates, risers, and fillet radii. A forging procedure may require coverage of parting lines and centerline. A wrought plate procedure may be looking for laminations rather than fusion-line lack of fusion. If the data sheet says "casting" and you run the weld scan plan, you have left the procedure even if the method is still UT.

3. Essential variables

Essential variables are the parameters that, if changed, take the examination outside the qualified procedure. Typical essential entries on a GI procedure include method and technique family (wet fluorescent continuous MT versus dry visible; Type I Method C PT versus Type II Method A), material or product-form family, thickness range, equipment class (yoke versus bench; contact versus immersion; film versus digital), magnetizing current type, penetrant family, probe angle and frequency band, calibration standard, lighting limits, and the named acceptance standard.

A Level II applies those values. A Level II does not rewrite them on the traveler to keep production moving. If the procedure lists two qualified techniques, the Level II may select the one the data sheet names. If the procedure lists one technique, a shop preference is not a second qualified technique.

Nonessential items are the ones the procedure says may vary without a revision — report-form layout if the required data are still captured, a listed equivalent couplant, which qualified Level II signs, or a recording sequence that still produces the same required fields. If the procedure is silent, treat the parameter as locked and ask the Level III. Silence is not permission.

4. Calibration and process control

Process control is how you prove the system still works today. GI procedures that invoke ASTM practices typically name the control piece and the frequency: a QQI or pie gauge and a lifting check for a yoke, a Ketos ring or similar for a bench unit, a UV-A intensity check and ambient-visible check for fluorescent work, a known-defect or process-control panel for PT, a densitometer and IQI check for film RT, an IIW or other calibration block for UT. The Level II runs the check the procedure names, at the interval the procedure names, and does not start production when the check fails.

Calibration is not the same sentence as acceptance. A system that meets the Ketos-ring hole requirement is a working MT system. It has not decided whether a 3 mm linear indication on a girder is rejectable. That decision lives in the acceptance pointer.

5. Lighting

Lighting is often an essential variable and is almost always a process-control item. Fluorescent techniques name a minimum UV-A irradiance at the surface and a maximum ambient visible light. Visible techniques name a minimum white-light illuminance at the surface. Direct visual procedures name viewing distance and angle. If the stem prints 1000 µW/cm², 20 lux, or 100 fc, those printed numbers are the item. They are procedure/code technique parameters, not ASNT exam secrets. If the meter reads below the minimum, you do not inspect. You fix lighting, or you stop.

6. Acceptance pointer

The last thing you read before you examine is where acceptance lives. A well-written GI procedure does not invent its own undercut table. It points: "Acceptance shall be in accordance with AWS D1.1 as specified on the data sheet," or "Acceptance shall be in accordance with the customer's specification attached as Appendix B," or "Reject all linear indications; rounded indications per the table on the data sheet." Find the pointer. Then open that document or that attached table. Do not substitute a remembered training number from a different code family.

The document hierarchy

On a real General Industry job the order of control is not "whatever the inspector remembers from class." Unless the contract prints a different order of precedence — in which case the printed order wins — use this stack:

1. Contract / purchase order / owner specification. This is what the buyer bought. It names the construction or product code, any tighter customer limit, hold points, and photo or report rules.
2. Invoked code or specification. For GI work that is often AWS D1.1 (structural steel), another AWS construction code, a customer product specification, or an aerospace process specification. This is usually where acceptance lives.
3. Employer NDT procedure. This is what the Level II holds. It implements the method practice (ASTM or other), lists essential variables, and points at the acceptance document.
4. Data sheet / technique card. This selects among options the procedure already qualified: joint, thickness row, technique letter, acceptance-table row, part identity. It is the lowest layer.

A data sheet that contradicts the contract or the invoked code is a wrong card, not a new code. Elevate. Do not average the two numbers. Do not pick the looser number because it is kinder to production.

ASTM practices versus AMS materials versus AWS D1.1

Keep the document types separate. Mixing them is the classic GI codes miss.

ASTM method practices tell how to examine when they are invoked. The five designations this exam family expects you to recognize as practices, not as secret ASNT tables, are:

• ASTM E1444 / E1444M — magnetic particle testing practice (aerospace-flavored MT practice; process control, magnetization, lighting, media)
• ASTM E1417 / E1417M — liquid penetrant testing practice (system, dwell, removal, developer, process control)
• ASTM E165 / E165M — liquid penetrant testing practice for general industry (same job family as E1417, different owner note; still a practice, still not a bridge-girder acceptance table)
• ASTM E94 / E94M — radiographic examination guide using industrial film (technique, IQI, density guidance)
• ASTM E164 — contact ultrasonic testing of weldments (scanning, calibration, coverage)

Those practices decide whether the system is set up in a controlled way. They do not, by themselves, tell you that a 3 mm linear MT indication on a painted girder is accept or reject. That sentence lives in the construction code or the customer specification the contract invoked.

AMS documents (SAE Aerospace Material Specifications) control materials and process families: penetrant materials, magnetic-particle media, cleaners, etchants, heat-treat or coating processes. An AMS-listed penetrant is a qualified material, not an acceptance table and not a substitute for AWS D1.1. A stem that says the penetrant shall meet AMS 2644 is asking about materials control. It is not asking you to reject a weld from AMS 2644.

AWS D1.1 / D1.1M, Structural Welding Code — Steel, is a construction code. When the contract invokes it, D1.1 can own visual geometric limits and the NDE acceptance the engineer specified for that weld. It is not an MT practice, not an RT technique guide, and not a pressure-vessel book. A D1.1 fillet on a building and a B31.3 girth weld on process piping do not share one reinforcement number. That is the point of sector literacy.

Related GI documents you may see in a stem follow the same type-logic. An owner paint spec can tighten undercut because paint will not cover a groove. A machining drawing can reject a linear indication that D1.1 would send to a different table. The Level II applies the document the contract named for that part, not the document that was on last week's job.

Essential versus what a Level II may adjust

Work this pattern until it is automatic.

Procedure MT-GI-04 Rev C. Scope: ferromagnetic welds 6–50 mm. Technique: wet fluorescent, continuous, yoke AC. Lighting: UV-A at or above the printed minimum; ambient at or below the printed maximum. Acceptance: AWS D1.1 table as printed on the data sheet. Essential-variable table lists technique family, current type, thickness range, and the named acceptance standard.

Scenario A — production wants dry visible because the fluorescent booth is busy. Dry visible is a different technique family. It is essential. The Level II refuses the swap, keeps the part in hold, and asks the Level III for a qualified procedure or a revision. Writing "dry vis — booth full" on the traveler is a procedure change, not helpful flexibility.

Scenario B — the weld is 12 mm and the data sheet names yoke AC. Thickness is inside 6–50 mm and the technique is the one the procedure qualified. Proceed. Selecting among already-qualified options is the data sheet's job.

Scenario C — the weld is 60 mm. Outside scope. Stop. Do not raise amperage by feel and call it still MT-GI-04.

Scenario D — UV-A is below the printed minimum. Lighting fails process control. Do not inspect. Fix the lamp or the distance, re-meter, then start.

Scenario E — the data sheet prints a looser undercut than the D1.1 row the contract invoked, and the contract does not authorize a relaxation. The data sheet is wrong. The contract and the invoked code sit above the card. Elevate. Do not apply the looser cell.

Scenario F — the report form in the booth is an older revision but every required field is still there, and the procedure lists form layout as nonessential. Complete the required data. That is a nonessential difference if and only if the procedure said so. If the procedure requires a named form revision, get the current form.

Realistic exam scenarios

A stem prints a procedure scope of 6–50 mm and a 55 mm forging. The correct move is that the part is outside scope, not that a Level II may extend range because the method is still MT.

A stem asks where you read whether a linear MT indication on a D1.1 girder is rejectable. The answer is the invoked construction code or the attached acceptance table, not ASTM E1444 by itself and not an unpublished ASNT chart.

A stem says the penetrant shall conform to an AMS materials specification and then asks whether that AMS document is the weld acceptance standard. It is not. AMS controls the material. Acceptance is still the code or customer table the procedure points at.

A stem offers four stacks. The stack that matches this section is contract → invoked code → employer procedure → data sheet.

A stem lets you choose a yoke or a bench unit when both appear in the procedure's qualified-technique list and the data sheet names the yoke. That selection is allowed. Swapping in a technique that is not on the list is not.