18.2 Codes, Standards, and Specifications

The ASNT NDT Level II visual general exam lists Codes, Standards, and Specifications as official VT topic 9. The specific exam (General Industry or Pressure Equipment) spends its codes items in the same neighborhood. Neither paper is asking you to recite an unpublished ASNT undercut chart. Both are asking whether you know which document controls, what kind of rule lives in each layer, and how to apply a table that is printed in a procedure or in the stem.

A code is a construction or in-service document with legal or contractual force once invoked (for example ASME B31.3, ASME Section VIII, AWS D1.1, API 1104). A standard or standard practice describes how a method is performed (for visual work, ASME Section V, Article 9 is the ASME technique article; other owners publish their own VT practices). A specification is often a customer, product, or project document that can add or tighten requirements. A procedure is the employer's work instruction that implements those layers for a part family. Learn the layers. Do not treat "the code" as one book.

The document hierarchy the Level II actually uses

On a real job the order of control is not "whatever the inspector remembers from class." It is this stack, unless the contract prints a different order of precedence — in which case the printed order wins.

1. Contract / purchase order / specification invoked by the order. This is what the buyer bought. It names the construction code, any customer visual standard, photo requirements, and hold points.
2. Construction or in-service code invoked by that contract. This is usually where acceptance lives: undercut, reinforcement, mismatch, cracks, underfill, fillet size.
3. Technique article for how VT is done when the construction code points at ASME rules — in ASME work that is Section V, Article 9. Direct versus remote, viewing access, and lighting adequate to resolve the specified condition live here, as implemented by the procedure.
4. Employer VT procedure (and any technique sheet or data card). This is what the Level II holds in the booth or at the vessel. It names the acceptance table, the measuring aids, the report form, and the essential viewing rules.

ASNT's NDT Level II outline is a topic list for a written exam. It is not a construction code and it does not publish AWS or ASME geometric limits as program secrets. If a stem prints a table, that table is the acceptance standard for the item.

B31.3 (process piping), Section VIII (pressure vessels), D1.1 (structural steel welding), and API 1104 (pipeline girth welds) are the examples this guide uses because they are the families a General Industry or Pressure Equipment candidate actually meets. They do not share one reinforcement number. A D1.1 fillet on a building and a B31.3 girth weld on sour service are different tables. That is the point of topic 9.

What Article 9 is — and is not

ASME Section V, Article 9 is a technique article for visual examination in the ASME system. Construction codes that send you to Section V are asking you to perform VT in a controlled way: direct visual when access allows the eye to view the surface under the article's and the procedure's distance and angle rules; remote visual (mirrors, borescopes, cameras) when direct access is not possible; and lighting sufficient to resolve the condition the referencing code wants evaluated.

Procedures that invoke Article 9 commonly print a maximum direct viewing distance and a minimum viewing angle (a pair you will often see written as 24 in (600 mm) and 30°), plus a minimum illumination at the surface (often written as 1000 lux / 100 fc). Those figures are code/procedure technique parameters, not ASNT exam secrets. If the stem prints 18 in, or 500 lux, or a remote-system resolution check, the printed numbers win. If the procedure is silent, you do not invent a shop custom and call it Article 9.

Article 9 does not tell you that 1/32 in of undercut is accept or reject on a particular vessel. That number, when it exists, lives in the construction code or the customer specification, and it is copied into the employer procedure's acceptance section. Candidates who treat Article 9 as a hidden accept/reject book fail items that ask "where do you read the undercut limit?"

Geometric acceptance is still VT acceptance

A crack that is prohibited is easy to remember and it is still a VT item. The outline also expects you to know that much of visual acceptance is geometric. The weld can be crack-free and still fail.

Conditions a construction-code visual table commonly addresses — without treating any one limit as an ASNT number — include:

• Undercut depth and sometimes length, often split by thickness or by whether the undercut is on a primary member
• Reinforcement or convexity height, and sometimes a minimum as well as a maximum
• Mismatch / hi-lo / alignment at the joint
• Underfill, incomplete groove fill, or undersized fillet leg and throat
• Overlap or rollover at the toe
• Surface porosity or clustered openings, when the code treats them as visual
• Arc strikes, craters, and visible incomplete fusion
• Cracks, which many construction codes simply do not allow

The unit matters. A table that limits undercut as a depth is not satisfied by recording only length. A table that limits reinforcement as a height above the plate is not satisfied by "it looks blended." A table that limits mismatch as a fraction of thickness requires the thickness row you are actually welding, not the row you memorized for a thinner coupon.

This is why "no crack, so accept" is a failing mental model for VT. Geometric conditions are first-class visual reject items.

How to apply a table that is printed in a procedure

Do not memorize a fake AWS or ASME chart for the ASNT exam. Learn the algorithm. Specific-exam stems print a fragment of a table and ask you to use it.

1. Confirm the governing document on the traveler or in the stem: procedure revision, construction code, any customer spec that the order of precedence places above the code.
2. Select the correct row. Tables split by thickness, weld type (groove versus fillet), process, or service category. Read the notes under the table; a general note often changes the row.
3. Select the correct column — discontinuity type. Undercut is not reinforcement. Face undercut is not root undercut if the table splits them.
4. Read the unit the cell uses: millimetres of depth, millimetres of height, millimetres of length in any 12 in, a fraction of thickness, or "not permitted."
5. Measure the way the table defines the dimension. Undercut depth is usually from the adjacent plate surface, not from the weld face. Reinforcement is usually from the plate to the highest point of the bead. Fillet size is leg or throat as the table states, with the gauge the procedure lists.
6. Compare each location. One station over the limit fails that criterion even if the rest of the weld is inside. Do not average a long undercut into an acceptable mean.
7. Record the measured value and the table cell you used when the procedure wants data, not only pass/fail.
8. If two documents disagree, use the contract's order of precedence. Do not pick the looser number because it is kinder to production. If the order is silent, elevate to the Level III; do not freelance a blend.

Worked pattern (illustrative, not an AWS secret): the procedure prints "for t = 10 mm, maximum reinforcement 3 mm, maximum undercut 0.5 mm, cracks not permitted." You measure reinforcement 3.4 mm, undercut 0.3 mm, no crack. Disposition is reject (or hold for repair) on reinforcement, even though undercut is inside and there is no crack. The printed cells, not a memory of another book's 1/8 in, decide the item.

If the stem prints a different trio of numbers, those numbers are the entire world of that question. Construction codes change by edition and by table. Your job is to apply the row in front of you.

Contract, specification, and the tighter rule

A customer specification can be tighter than the construction code: zero undercut for a paint-critical beam, a sanitary blend for a food-grade tube, a photo of every final weld, a ban on arc strikes that the code would treat case by case. The contract can also invoke a looser project exception — only if the exception is written. The Level II does not grant exceptions.

When a stem says the contract requires VT to AWS D1.1 and the owner's spec, and the owner's spec is silent on reinforcement, you use D1.1's printed reinforcement cell. When the owner's spec states a smaller maximum than D1.1, you use the owner's number. That is specification literacy, not a third construction code.

What the Level II may not substitute

The Level II applies the named procedure and the named acceptance standard. The Level II does not:

• Swap B31.3 limits onto a D1.1 job because the shop welded pipe last week
• Replace a printed table with a remembered training number
• Use Article 9 viewing-distance rules as if they were acceptance limits
• Ignore a geometric cell because the weld is crack-free
• Write a new acceptance note on the traveler to keep production moving

Those substitutions are procedure changes. They belong to the Level III or the document owner. Topic 10 in the next section is where that control is made explicit; topic 9 is where you learn which book you are not allowed to replace.

Realistic exam scenarios

A stem asks for the controlling stack: contract, then construction code, then Article 9 technique, then employer procedure. A stem shows a crack-free weld with reinforcement over the printed maximum: reject or hold on the geometric cell. A stem prints 1/8 in maximum reinforcement and your memory of another code is 1/16 in: apply 1/8 in. A stem asks where undercut depth is published: the construction code or customer spec as copied into the procedure, not ASNT and not Article 9 by default. A stem mixes API 1104 and ASME VIII: you do not average them; you use the document the contract named for that weld.