What this module covers
API 1104 is the pipeline welding standard published by the American Petroleum Institute. Part C on API 1104 is open book: 60 scorable items, with 5 more unscored pretest items on the English form, and 135 minutes to answer on that form. The 22nd edition is on screen as a PDF, and some navigation may be disabled.
This module covers the layout of the book and the Fabrication content: production welding practice and repairs (25% minimum), plus the Materials and Design slice (5% minimum).
By the end you will be able to:
- name the API 1104 section for a topic by title,
- find the rules for materials, filler metal and joint preparation,
- apply the production welding rules to a field scenario,
- follow the repair path from a found defect to an accepted repair.
We name sections by title only. Keep your own copy of API 1104 (22nd edition) open.
Finding your way around API 1104
The section map
API 1104 reads in the order a pipeline is built: specify, qualify, weld, inspect, accept, repair.
| Section (by title) | What you look for there |
|---|---|
| Scope, references and definitions | What the standard covers, the meaning of its terms |
| Specifications | Equipment and materials: pipe, fittings, filler metal, shielding |
| Qualification of welding procedures | Procedure specification, essential variables, procedure test welds and tests |
| Qualification of welders | Single and multiple qualification, tests, records |
| Design and preparation of a joint for production welding | Alignment, clamps, cleaning, weather, preheat, identification |
| Inspection and testing of production welds | Rights of inspection, methods, who interprets results |
| Acceptance standards for NDT | Limits for each imperfection type by method |
| Repair and removal of defects | Authorization, repair procedures, inspection of repairs |
| Procedures for NDT | Radiography, magnetic particle, penetrant, ultrasonic |
| Mechanized and automatic welding | Separate procedure and operator rules |
| Annexes | Alternative acceptance standards and in-service welding, among others |
Navigating without search
Assume search is off. The table of contents and bookmarks are your index. Practice going from a question's topic to a section title, then to the paragraph. The acceptance standards section is the most used part of the book on exam day, so learn its internal order by imperfection type.
Trap. Answering from D1.1 or ASME habits. Pipeline rules use their own terms (for example, imperfections versus defects) and their own variable list.
Materials, filler metal and joint preparation
Materials
The specifications section tells you which pipe and fitting materials the standard is written around and how materials are grouped for qualification. Groups are based on strength, so a procedure qualified on one group may not cover a stronger one. Chemistry and thickness also matter.
Filler metal
Filler metals are grouped for procedure qualification. A change from one group to another is a procedure change you look up in the essential variables (module 2). The specifications section also covers storage and handling: damp or damaged consumables are not used.
Joint preparation
Joint design is part of the procedure: bevel angle, root face, root opening and the type of joint. On the line, the pipe ends must be clean, free of damage and prepared to the procedure before welding.
Worked navigation (invented example). A question gives a pipe grade with an invented strength of 480 MPa and asks whether a procedure qualified on pipe of 360 MPa covers it. Path: qualification of welding procedures; essential variables; the base material grouping; check whether both strengths fall in the same group.
Production welding practice
Alignment and clamps
Pipe ends are aligned to keep high-low within the standard's limits and spread evenly around the joint. Line-up clamps hold alignment during the root pass. The standard says when a clamp may be removed, based on how much root bead is complete. Removing it early risks cracking the root.
Between passes and between days
Each bead is cleaned of slag and scale before the next. The time between the root bead and the second bead may be limited by the procedure, since a delay can let the root crack.
Weather and preheat
Welding stops when weather would harm the weld, unless the joint is protected. Preheat follows the procedure; if the procedure calls for preheat and the joint is below it, welding waits.
Identification
Each welder's work is identified as the company requires, so a rejected weld can be traced to the welder.
Worked example (invented values). A procedure gives a minimum preheat of 100 °C. A crew starts welding with the joint at 60 °C because the wind cooled it. Steps: stop; bring the joint to the procedure temperature; check whether wind protection is needed; record the departure if the company requires it; any weld deposited below preheat is evaluated as the company directs.
Trap. Treating preheat as a guideline. It is a procedure value; below it, the weld is not made to the procedure.
Repair and removal of defects
The repair path
- Find and classify. Inspection finds an imperfection. The acceptance standards decide if it is a defect.
- Authorize. Some repairs, especially cracks, need the company's authorization. Some cracks are not repairable and the weld is cut out.
- Use a qualified repair procedure. Repairs are welded to a qualified procedure; the standard lists what that procedure must cover.
- Confirm removal. The excavation is checked to show the defect is gone before rewelding.
- Reinspect. The repaired area is inspected by the method that found the defect, at least.
Mechanized and in-service welding
Mechanized welding has its own procedure and operator qualification rules in a separate section. In-service welding, meaning welding on a pipeline that is carrying product, adds two hazards: burning through the wall and hydrogen cracking from the fast cooling caused by the flowing product. The in-service annex covers how procedures and welders are qualified for it.
Worked example (invented). Radiography finds a crack 15 mm long in a girth weld. Steps: acceptance standards say whether any crack is acceptable; repair section says whether a crack of this kind may be repaired and who must authorize it; if repair is allowed, weld it under the qualified repair procedure and reinspect.
Trap. Repairing a crack without the authorization the standard requires, or reinspecting with a different method that cannot find the original defect.
Check yourself
The three questions below cover finding the right section, line-up clamp removal and the repair path for a crack.
Where to look in your own books
- API 1104 22nd edition, table of contents: the section titles above
- API 1104, specifications: materials and filler metal
- API 1104, design and preparation of a joint for production welding
- API 1104, repair and removal of defects
- API 1104, mechanized welding section and the in-service welding annex
- AWS API 1104 Endorsement Description (Rev. 11.05.2026): exam format and code reference policy