API 570 Piping Repairs, Alterations and Rerating: Who Authorizes What

Short answer: Under API 570, a repair restores piping to safe operation at its existing design conditions; an alteration is a physical change with design implications; a rerating changes the design pressure or temperature. All repair and alteration work is done by a qualified repair organization and must be authorized by the authorized piping inspector before it starts. Alterations and some repairs also need the piping engineer's approval, and a rerate needs calculations, current inspection data and documented acceptance before the new rating is used.

This guide maps who does what, the difference between temporary and permanent repairs, the NDE and pressure-test expectations after repair work, and how rerating is justified. The provisions described follow the API 570 4th edition (2016) text. The 5th edition, published in February 2024, added requirements on the review and deferral of inspection repair recommendations and defined an Inspection Supervisor role; API RP 574 was revised at the same time with more guidance on rerating, repairs and alterations (API trade press, api.org). Confirm any clause, number or limit against your licensed copy of the current edition before you apply it. This page paraphrases the code; it does not reproduce it.

Repair, alteration or rerating: getting the category right

The category decides who has to sign off, so the first question on any piping work package is which one it is.

Repair. Work needed to restore piping to a condition suitable for safe operation at its design conditions. Replacing a corroded spool with an identical one, welding a sleeve over a pinhole leak, or cutting out a cracked weld and rewelding it are repairs. If the work changes the design temperature or pressure, it stops being only a repair and the rerating requirements also apply.

Alteration. A physical change to a component that has design implications affecting its pressure-containing capability or flexibility beyond the scope of its original design. Adding a new branch connection, rerouting a line so its supports and flexibility change, or changing to a different material are typical alterations. The 4th edition is explicit that comparable or duplicate replacements, and replacements in kind, are not alterations. That distinction matters: an owner replacing a spool with the same specification, same size and same schedule is doing a repair, not an alteration, even if the job is large.

Rerating. A change in the design pressure or design temperature rating of a piping system; check the current edition for the full definition. A rerating can go up or down. A downrate to keep corroded piping in service at a lower pressure is still a rerating and still needs the full justification.

Ambiguous jobs are common. A replacement spool in an upgraded alloy is a material change, so most owners treat it as an alteration even though the geometry is the same. A new small-bore vent on an existing line adds a branch connection, which is an alteration. If the category is unclear, the safe path is to treat the job under the stricter category and record why.

Who authorizes and approves: the role map

API 570 separates the people who decide from the people who do the work. The table summarises the roles as the 4th edition describes them.

Three points come up repeatedly in audits. First, authorization comes before the work. An inspector signing a repair after the fact is documenting, not authorizing. Second, "general prior authorization" exists so that routine, limited repairs, for example replacing a gasket or a like-for-like small spool, do not stall waiting for a signature, but it has to be defined and limited in writing. Third, the 5th edition's Inspection Supervisor role means owners should check how their programme now assigns oversight of inspectors; confirm the definition in the current edition.

Temporary repairs: sleeves, clamps, box enclosures and wraps

Most in-service piping repairs start as temporary repairs, because the line cannot be taken out of service until the next shutdown. API 570 recognises this and sets the expectation that a temporary repair is exactly that.

The 4th edition recognises full-encirclement welded split sleeves, box-type enclosures, mechanical leak clamps and non-metallic composite wraps as temporary repair options, designed and installed under the inspector's authorization and, where design is involved, with the piping engineer. ASME PCC-2 is the referenced source for many of these methods; see our ASME PCC-2 guide.

The governing rule is about time: temporary repairs should be removed and replaced with a suitable permanent repair at the next available maintenance opportunity. The temporary repair may stay longer only if the piping engineer has evaluated it and the decision is documented. Many plants carry long lists of clamps that were installed "until the next turnaround" several turnarounds ago, and that is precisely what the code language is aimed at.

Practical points for a temporary repair package:

• Know the damage under the repair. A sleeve over a crack is very different from a sleeve over general thinning. The 4th edition calls for piping engineer consultation before repairing cracks in service, because a crack can keep growing under a sleeve.
• Measure the wall where the sleeve or enclosure will be welded. Welding onto metal that is too thin or laminated creates a new defect. UT thickness and lamination checks at the weld landing zone are standard NDE for this.
• Record it in the inspection programme. Each temporary repair needs a location, a description, the date installed, the basis for its acceptance and a due date for permanent repair.
• Monitor it. Clamps and enclosures can hide continued corrosion. Programmes typically add an external visual and, where practical, thickness checks adjacent to the repair at each inspection.

Permanent repairs: replacement, insert patches and weld repairs

Permanent repair options include replacing the damaged section, excavating and weld-repairing defects, and installing insert (flush) patches. The 4th edition sets specific expectations for insert patches: they are installed with full-penetration groove welds, the corners are rounded with a minimum radius, and for Class 1 and Class 2 piping the patch welds are examined 100 percent by radiography or ultrasonic testing using NDE procedures the inspector has approved. The exact radius and any other dimensional limits should be taken from your current edition.

Weld repairs of defects follow the welding requirements API 570 sets for repair work: qualified welding procedures and welders, under the construction code or the applicable code for the repair, with preheat and postweld heat treatment as that code requires. API 570 also describes alternatives to postweld heat treatment in some cases; these are design decisions for the piping engineer, not field choices.

On-stream welding, including hot taps, needs owner-user approval. The industry practice reference for safe hot tapping is API RP 2201, and the decision to weld on live piping typically involves operations, the piping engineer and the inspector together.

For class definitions that drive the insert-patch examination requirement, see our API 570 piping service classes guide.

NDE and pressure testing after repair

API 570 makes the inspector responsible for specifying examination and testing of repair work. In practice, the NDE package for a piping repair usually combines:

• Visual examination of fit-up, weld profile and finished welds.
• Surface examination by magnetic particle (MT) or liquid penetrant (PT) on excavations before rewelding, on fillet welds of sleeves and enclosures, and on finished welds where the inspector requires it.
• Volumetric examination by radiography or UT of butt welds and insert patches, with 100 percent coverage of insert-patch welds in Class 1 and 2 piping under the 4th edition.
• UT thickness of the parent metal around the repair, both to confirm the repair landing zone and to establish a new baseline CML.
• Hardness testing where the service or the welding procedure calls for it.

Acceptance criteria normally come from the construction code, for example ASME B31.3 Table 341.3.2 for process piping, unless the owner specifies otherwise.

On pressure testing, the 4th edition expects a pressure test after alterations and major repairs, unless the inspector, consulting the piping engineer where required, accepts NDE in place of the test because a test is impractical or unnecessary. When a test is waived, the substituted NDE and the reasoning should be documented. Our companion guide on pressure testing after repair covers the equivalent vessel rules under API 510, which follow the same logic.

Rerating: what has to be in the file

A rerate is the most documentation-heavy of the three activities, because it changes the basis every future inspection decision rests on. The 4th edition lists the elements a rerate must show; in plain language they are:

1. Calculations by the piping engineer or the inspector demonstrating the system is adequate at the new conditions.
2. Current inspection records showing the piping is in condition to support the new rating, typically recent thickness data across the circuits affected and an evaluation of any known damage.
3. A leak test to the new conditions, unless the rerate is supported by an earlier test at or above the new requirement or another exemption applies under the code.
4. Pressure relieving devices verified to protect the system at the new conditions.
5. Component adequacy: flanges, valves, fittings and other components checked against the new pressure-temperature rating.
6. Flexibility: the system checked for the new temperature where thermal expansion changes.
7. Updated records, including the design documentation and the nameplate or line list information.
8. Acceptance by the inspector or piping engineer.

Downrating corroded piping is the most common rerate in refineries. It can keep a line running until the next turnaround, but it depends entirely on good thickness data: the calculation is only as good as the minimum thickness used. Where localised damage is involved, some owners commission a fitness-for-service assessment under API 579-1/ASME FFS-1 as part of the rerate basis. That is an engineering assessment the owner commissions from qualified engineers; the NDE provider's role is to supply data of the quality the assessment needs. See the API 579 overview for context.

Repair recommendations and deferral under the 5th edition

Inspection findings become repair recommendations with due dates. A recurring audit finding is recommendations that quietly slip past their due date. API's announcement of the 5th edition says it introduces recommendations and requirements on the review of inspection repair recommendations and the deferral of their due dates (api.org). Owners should read that section in the current edition and check that their own procedure covers who may defer, what justification is required and how deferrals are recorded. The code text sets the rule; this page cannot reproduce it.

Whatever the edition, a defensible deferral usually includes current NDE showing the condition has not worsened, an engineering review of the remaining margin, any interim measures such as increased monitoring, and a new due date approved by the people the code names.

Common mistakes and the jurisdictional overlay

• Calling an alteration a repair to avoid piping engineer involvement, for example adding a branch connection under a repair work order.
• Authorization after the fact. The signature date is after the weld date.
• Clamps with no due date. Temporary repairs not tracked to replacement.
• Repairing a crack without knowing why it cracked. Vibration, environmental cracking or a welding defect each need a different fix.
• No new baseline. Replaced spools not given new CML readings, so the next corrosion rate is calculated across old and new metal.
• Rerating on stale data. Using thickness readings from several years ago to justify a new rating.

In the US, PSM-covered facilities must keep piping inspection, testing and the correction of deficiencies in line with recognised and generally accepted good engineering practice (29 CFR 1910.119(j)), and alterations fall under management of change. Some states and cities regulate certain piping through boiler and pressure vessel laws. In Canada, piping repairs and alterations often fall under provincial pressure equipment regulations that require registered procedures and, in some cases, regulator involvement; Alberta (ABSA) and Ontario (TSSA) each have their own requirements. Confirm with your jurisdiction.

How Atlantis supports piping repairs and rerates

Atlantis NDT performs the NDE the authorized inspector specifies for repairs, alterations and rerates: UT thickness and lamination checks at sleeve and patch landing zones, MT and PT of excavations and fillet welds, radiography and UT of insert-patch and replacement butt welds, and fresh CML thickness surveys to support a rerate calculation. Technicians are ASNT-certified and work under ASNT Level III oversight. Results go to the owner's API 570 inspector, who remains inspector of record; Atlantis does not authorize, approve or design repairs, and does not perform fitness-for-service or RBI assessments. Request a quote for repair NDE and we will respond within 24 hours.

Frequently asked questions

Who authorizes piping repairs under API 570?

The authorized piping inspector authorizes repair work before it starts and sets hold points. For alterations, the piping engineer must also be consulted and approve before the inspector authorizes the work.

What is the difference between an alteration and a repair in API 570?

A repair restores piping to safe operation at its design conditions. An alteration is a physical change with design implications for pressure-containing capability or flexibility beyond the original design. Like-for-like replacements are not alterations.

Is a replacement spool an alteration?

Not if it is a comparable or duplicate replacement in kind. A change of material, size or routing that affects design usually makes it an alteration.

How long can a temporary piping repair stay in place?

API 570 expects temporary repairs to be replaced with permanent repairs at the next available maintenance opportunity. They may remain longer only if the piping engineer evaluates and documents that decision.

Do insert patches need radiography under API 570?

Under the 4th edition, insert patch welds in Class 1 and Class 2 piping are examined 100 percent by RT or UT using inspector-approved procedures. Check the current edition.

Is a pressure test required after a piping repair?

A pressure test is normally expected after alterations and major repairs, but the inspector, with the piping engineer where required, may accept NDE in its place when a test is impractical. The substitution should be documented.

What does a piping rerate under API 570 require?

Calculations, current inspection records supporting the new conditions, a leak test or valid exemption, relief device verification, component and flexibility checks, updated records, and acceptance by the inspector or piping engineer.

Can a contractor approve a piping repair?

No. A contractor can be the repair organization or the NDE provider, but authorization and approval sit with the owner's authorized inspector and piping engineer.

Does API 570 reference ASME PCC-2?

Yes. API 570 points to ASME PCC-2 for repair methods such as sleeves, enclosures and composite wraps. PCC-2 describes methods; API 570 sets who authorizes them.

What changed in the API 570 5th edition for repairs?

API's announcement highlights new requirements on reviewing and deferring inspection repair recommendations and a defined Inspection Supervisor role. Read the current edition for the detail.

Have a repair package to scope before a shutdown? Ask Atlantis NDT for repair and rerate NDE. For the vessel equivalent, see API 510 repairs, alterations and rerating. Get a quote within 24 hours.