API 510 Pressure Vessel Inspection Support in Mississippi

Short answer: Mississippi regulates unfired pressure vessels through the Boiler and Pressure Vessel Safety Branch of the State Department of Health. Vessels subject to internal corrosion receive a certificate inspection every two years. At refineries, LNG, chemical and fertilizer plants, the owner's API 510 Authorized Inspector (AI) also runs a code-based programme that sets internal, on-stream and external intervals from measured corrosion. Atlantis NDT performs the nondestructive examinations both regimes rely on: UT thickness at CMLs, corrosion mapping, PAUT, TOFD, WFMT, ET, RT, PT and VT. Atlantis performs the NDE; your API 510 Authorized Inspector remains inspector of record and signs the inspection report.

The state's approach hinges on one question that is also at the heart of API 510: is the vessel's content corrosive to it? Mississippi's rules put corrosive-service vessels on a fixed two-year certificate cycle, and allow vessels shown to be in non-corrosive service to go without internal inspection. Good thickness data answers that question for both the state inspector and the AI. To get started, request an NDE scope for your AI's plan.

Where API 510 pressure vessels are in Mississippi

Direct answer: Mississippi's heaviest concentration of API 510 vessels is on the coast at Pascagoula's Bayou Casotte, home to a major refinery and an LNG terminal. Inland, there are a naphthenic refinery at Vicksburg, a nitrogen fertilizer complex at Yazoo City, a titanium dioxide plant at DeLisle, and pulp and paper, steel, gas-storage and power vessels across the state.

Pascagoula and Bayou Casotte

The Chevron Pascagoula refinery is one of the largest in the United States, and its vessel population is correspondingly broad: crude and vacuum columns, fluid catalytic cracking reactor and regenerator, hydrocrackers and hydrotreaters with heavy-wall reactors, reformers, alkylation units, sulfur recovery, amine treating and sour water stripping. Expected damage includes sulfidation, high-temperature hydrogen attack considerations in hydroprocessing, wet H2S cracking and blistering, ammonium bisulfide corrosion in reactor effluent systems, and acid attack in alkylation. Next door, the Gulf LNG terminal runs cryogenic and pressurised vessels in natural gas service. The shipyard and fabrication shops along the Pascagoula River add air receivers, compressed-gas vessels and process water systems. Context: refining NDT consulting in Pascagoula and Level III support for Pascagoula shipyards.

Gulfport, Biloxi and DeLisle

West along the coast, the titanium dioxide plant at DeLisle near Pass Christian uses chloride-process chemistry, which brings chlorine, titanium tetrachloride and acid gas handling with severe corrosion and cracking risks for vessels and their nozzles. The Port of Gulfport adds terminals and cold-storage refrigeration, and power stations along the coast run deaerators, feedwater heaters and air receivers. See NDT consulting in Gulfport and practical NDT in Gulfport.

Vicksburg, Yazoo City and the Delta

Vicksburg's Ergon refinery processes crude into naphthenic specialty oils and asphalt, with vacuum distillation, hydrotreating and solvent units whose vessels see naphthenic acid corrosion in hot sections, plus wet H2S and amine service downstream. Up the Yazoo River, the CF Industries Yazoo City complex makes ammonia and nitrogen products, so ammonia converters, synthesis loop separators, ammonia storage vessels and nitric acid equipment are present. Ammonia service raises the risk of stress corrosion cracking in carbon steel, and nitric acid service affects stainless steels. The Grand Gulf nuclear station near Port Gibson is NRC-regulated, and the state law exempts equipment operated under NRC licences, but non-licensed balance-of-plant vessels are handled differently.

Jackson, Hattiesburg and the oil patch

Around Jackson and in the central and southern counties, manufacturing plants, utility stations, and natural gas storage and processing facilities run compressors, scrubbers, separators and dehydration vessels. Oil and gas production in southwest Mississippi and the Laurel area runs separators and treaters; the state can exempt oil and gas vessels in remote areas case by case, which matters for lease equipment. See practical NDT in Jackson.

Columbus and northeast Mississippi

The Golden Triangle around Columbus hosts steel production, pulp and paper, aerospace and chemical manufacturing. Pulp mills run digesters, flash tanks and steam accumulators where caustic and sulfide liquors cause cracking and thinning; steel mills run large air receivers, industrial gas vessels and cooling systems. See NDT consulting in Columbus.

What API 510 requires, in plain terms

Direct answer: API 510 governs in-service inspection, repair, alteration and rerating of pressure vessels and their relief devices. Each vessel needs an inspection plan; external and internal or on-stream inspection dates come from measured corrosion rates and remaining life; and the AI evaluates and accepts the results. In Mississippi, those intervals run alongside the state's biennial certificate for corrosive-service vessels.

The American Petroleum Institute's current edition of API 510 is the 11th, published in October 2022. Older editions are common online, so confirm requirements against the edition your programme uses. In paraphrase, the current edition limits external inspection to the lesser of five years or the internal or on-stream interval, and internal or on-stream inspection to the lesser of half the remaining life or ten years; where remaining life is less than four years, the interval may be the full remaining life up to two years. An RBI programme that meets the code's conditions can set different intervals; that assessment is done by the owner's engineers or a specialist.

Each vessel's inspection plan names the credible damage mechanisms (API 571 is the reference), the inspection type and coverage, the condition monitoring locations (CMLs), the NDE techniques chosen to detect and size each mechanism, and the next due dates. On-stream inspection may replace an internal entry when the code's conditions are met, and in practice that turns on whether external NDE can see the damage that matters. Corrosion rates come from thickness trends at the CMLs; remaining life is the margin above the required thickness divided by the governing rate.

Relief devices are inspected and tested at intervals tied to service, with API RP 576 as the reference practice. Repairs, alterations and rerating are authorised and accepted by the AI under API 510; Mississippi adopts the National Board Inspection Code, and its rules require a Mississippi serial number on every vessel subject to the law. For the arithmetic, see API 510 interval calculation explained; for the difference between the AI and a state-commissioned inspector, see API 510 vs NBIC commissioned inspector.

NDE methods for API 510 work in Mississippi

Direct answer: UT thickness and corrosion mapping establish the corrosion rates that both the AI and the state's corrosive-service test depend on. PAUT, TOFD and WFMT address cracking in hydroprocessing, sour, amine and ammonia service; ET covers exchanger bundles; RT, PT and VT cover welds, alloys and overall condition.

We document coverage, scan density, the damage mechanism targeted and any areas not examined for every vessel, so the AI and, where relevant, the state or insurance inspector can see what the data supports. The coast's heat, humidity and salt make insulated vessels prime candidates for corrosion under insulation; see CUI inspection support. For mechanism background, see our API 571 damage mechanisms guide and API 510 intervals in sour service.

Mississippi is an NRC Agreement State. Radioactive materials, including industrial radiography sources, are licensed by the State Department of Health's Division of Radiological Health. RT on Mississippi sites is performed by crews licensed for work in the state, with exclusion zones agreed with site operations during scoping.

How Atlantis supports your Authorized Inspector

Direct answer: Atlantis turns the AI's plan into Level III-reviewed procedures, performs the examinations with ASNT-certified technicians and delivers a digital report that the AI evaluates and signs, and that a commissioned inspector making the state certificate inspection can also use. We are not an Authorized Inspection Agency and we do not supply API-certified inspectors.

In Mississippi, certificate inspections are made by state inspectors or by insurance company inspectors commissioned by the state board, while the API 510 programme belongs to the owner's AI. We work underneath both as the NDE contractor:

1. Plan intake. Vessel list with Mississippi serial numbers and National Board numbers, CML maps, damage mechanisms, inspection type, API 510 due dates and certificate expiry dates.
2. Procedures. UT, mapping, PAUT, TOFD, WFMT, ET and RT techniques prepared or reviewed by an ASNT NDT Level III, with coverage plans where on-stream inspection is proposed instead of entry.
3. Field execution. Crews mobilised to your site; the schedule is agreed during scoping around unit status, permits, confined-space entry and port security where it applies.
4. Data QA. Readings checked against history; anomalies re-shot while scaffold and access remain.
5. Digital report. CML IDs, readings, C-scans, indication tables, photographs, calibration and equipment records and technician certifications in Atlantis's reporting platform.
6. Evaluation and sign-off. The AI determines corrosion rates, remaining life, intervals and repairs; we can calculate corrosion-rate and remaining-life figures from our data for the AI's review. Atlantis performs the NDE; your API 510 Authorized Inspector remains inspector of record and signs the inspection report.
7. Next cycle. CML numbering carries forward so the next survey trends like for like.

Where the owner's engineers run RBI or a fitness-for-service assessment, our maps and flaw sizes feed work they or a specialist carry out. See API 510 pressure vessel NDE support and pressure vessel inspection services.

Mississippi regulations that sit on top of API 510

Direct answer: The Boiler and Pressure Vessel Safety Act (Mississippi Code Title 45, Chapter 23) is administered by the State Department of Health's Boiler and Pressure Vessel Safety Branch. Vessels subject to internal corrosion receive a biennial certificate inspection; federal OSHA enforces process safety. Confirm how your site's vessels are classified with the branch.

The state law and rules. Mississippi enacted its Boiler and Pressure Vessel Safety Act in 1974. The Department of Health's Boiler and Pressure Vessel Safety Branch in Jackson administers it, and a technical advisory committee is empowered to make the rules. According to the National Board's jurisdictional synopsis (last reviewed by the state in 2023), Mississippi adopts the current ASME Code Sections I, IV and VIII Division 1 and the current NBIC, requires the manufacturer's data report to be filed before operation, and requires every boiler and pressure vessel subject to the law to be stamped with a Mississippi serial number. Non-code designs need approval as a Mississippi Special.

Inspection frequency. The synopsis states that pressure vessels subject to internal corrosion receive a certificate inspection every two years, while vessels not subject to internal corrosion are inspected at intervals set by the board. An internal inspection is not required where the contents are known to be non-corrosive to the vessel material, whether from their chemical composition, from evidence that they are adequately treated with a corrosion inhibitor, or from evidence that the vessel parts are isolated from the contents. A two-month grace period is allowed, and the board may permit longer periods. Thickness data and corrosion-rate history are the most direct evidence for those decisions.

Exemptions. The listed exemptions include equipment on federal property; pipelines and related facilities inspected by a federal or other state agency; vessels built and operated under NRC licences; DOT-specification transport containers; small and low-pressure vessels; LP-gas equipment covered by the state's Liquefied Compressed Gas Equipment Inspection Law; and oil and gas vessels in remote areas, determined case by case. Unlike some Gulf states, the synopsis does not list a general exemption for refinery or chemical-plant vessels or an owner-user inspection agency route, so confirm with the branch how vessels at your facility are handled and who performs the certificate inspection.

Who inspects. State inspectors and insurance company inspectors commissioned by the board. Insurers must report inspections on standard forms within 30 days and notify the chief inspector immediately if a vessel is refused or suspended for unsafe conditions. Inspectors holding a National Board commission can receive a Mississippi reciprocal commission.

OSHA. Mississippi has no OSHA state plan, so private-sector process safety falls under federal OSHA's Process Safety Management standard, 29 CFR 1910.119. Its mechanical integrity element, paragraph (j), requires written procedures, inspection and testing following RAGAGEP, documentation and correction of deficiencies. API 510 is the RAGAGEP Mississippi refiners and chemical producers cite for pressure vessels, and EPA's Risk Management Program (40 CFR Part 68) Program 3 sits alongside it.

Pipelines and LNG. The Mississippi Public Service Commission oversees intrastate gas pipeline safety with PHMSA; interstate lines fall to PHMSA under 49 CFR Parts 192 and 195. LNG facilities are subject to federal LNG rules (49 CFR Part 193) for the regulated parts of the terminal, so confirm the boundary between those rules, the state law and API 510 for each vessel at an LNG site.

Planning around turnarounds, the biennial cycle and storm season

Direct answer: Align certificate expiry dates with API 510 due dates so one examination serves both, book Pascagoula turnaround NDE early, and plan coastal external and CUI work around the June-to-November hurricane season.

• Certificate alignment: list each vessel's biennial certificate date next to its API 510 internal and external dates; schedule examinations that answer both inspectors' questions at once.
• Corrosive versus non-corrosive service: if you plan to rely on non-corrosive service to avoid internal inspections, build the evidence: stable thickness trends at representative CMLs, inhibitor records or proof of isolation.
• Turnarounds: Pascagoula outages compete for crews with Louisiana and Alabama plants; scope heavy-wall TOFD, reactor PAUT and WFMT of amine and sour vessels well in advance.
• Hurricane season: plan post-storm inspection scopes with the AI before the season, including flood-exposed vessels and insulation that may have taken on water.
• Heat: summer heat shortens confined-space entries; on-stream mapping and PAUT can reduce the number of entries needed.
• Fertilizer and LNG sites: ammonia and cryogenic service bring their own isolation, purging and temperature constraints; agree them during scoping.

API 510 inspection support across Mississippi

Direct answer: Atlantis supports API 510 and certificate-cycle vessel programmes from the coast to the Delta and the Golden Triangle. Crews are mobilised to your site, and the schedule is agreed during scoping; we do not have a local office.

• Pascagoula and Moss Point: refinery, LNG, shipyard and chemical vessels; see NDT training in Pascagoula for in-house technicians.
• Gulfport, Biloxi and DeLisle: chemical, port, refrigeration and power vessels; see refining NDT consulting in Gulfport.
• Vicksburg and Yazoo City: naphthenic refining and nitrogen fertilizer vessels.
• Jackson and central Mississippi: manufacturing, utility, gas storage and processing vessels; see NDT training in Jackson.
• Columbus and the Golden Triangle: steel, pulp and paper, aerospace and chemical vessels; see steel NDT consulting in Columbus.

Sibling hubs for the state: API 653 tank inspection in Mississippi and API 570 piping inspection in Mississippi. For every NDT method statewide, see NDT inspection services in Mississippi; for procedures and Level III support, NDT consulting in Mississippi; for technician training, ASNT NDT training in Mississippi; and for hands-on practice, practical NDT in Mississippi.

One data set, two inspectors: making certificate and API 510 inspections work together

Direct answer: At Mississippi sites, the state or insurance inspector and the API 510 AI often look at the same vessel for different reasons. A single NDE package with fixed CMLs, stated coverage and traceable records lets both rely on one set of measurements instead of paying for two.

The certificate inspector wants to know whether the vessel is safe to operate for the next two years and whether its service is corrosive. The AI wants a corrosion rate, a remaining life, an interval and a view on cracking risk. Those questions overlap almost completely. Where they part is in documentation: the certificate inspector reports on National Board forms within the state's deadlines, while the AI's record lives in the owner's mechanical integrity system under PSM.

Our reports are built to serve both. Each vessel section states the Mississippi serial number and National Board number, the damage mechanisms targeted, the CMLs measured and the coverage achieved. Calibration records, probe data and technician certifications are attached; technicians are certified under their employer's ASNT SNT-TC-1A written practice with ASNT Level III oversight, and procedures carry Level III review. Areas not examined are listed with reasons. Results can be tracked against certificate and API 510 due dates in our inspection-management ERP, mapped onto a digital twin, or delivered in formats shown on NDT report templates. Ask for a combined certificate and API 510 NDE scope.

What to send us for a Mississippi quote

Direct answer: Send the vessel list with Mississippi serial numbers, the AI's plan and CML maps, the last API 510 and certificate reports, certificate expiry dates, access status and target dates. We quote within 24 hours of receiving that information.

1. Vessel tags, U-1 data reports or nameplate data, Mississippi serial and National Board numbers, drawings and materials.
2. The last API 510 report, the last certificate inspection report and thickness history.
3. The AI's inspection plan, CML map and damage mechanisms of concern.
4. Certificate expiry dates and whether each vessel is classed as corrosive or non-corrosive service.
5. Inspection type, cleaning and entry status, insulation, scaffold and site security requirements.
6. Dates, outage window and safety orientation requirements.

Send us your vessel list and we will reply with questions or a draft scope.

Frequently asked questions: API 510 in Mississippi

Does Mississippi require pressure vessel inspections?

Yes. Under the Boiler and Pressure Vessel Safety Act, pressure vessels subject to internal corrosion receive a certificate inspection every two years, and other vessels at intervals set by the board. Confirm current requirements and exemptions with the Department of Health's Boiler and Pressure Vessel Safety Branch.

Who regulates pressure vessels in Mississippi?

The Mississippi State Department of Health, through its Boiler and Pressure Vessel Safety Branch in Jackson. Inspections are made by state inspectors or by insurance company inspectors commissioned by the board.

Is an internal inspection always required in Mississippi?

No. The rules do not require internal inspection where the contents are known to be non-corrosive to the vessel, are adequately treated with a corrosion inhibitor, or are isolated from the vessel parts. Thickness trends are the usual evidence. Under API 510, the AI still decides whether internal or on-stream inspection is needed.

Do Mississippi refinery vessels need both a state certificate and an API 510 inspection?

The National Board synopsis does not list a general refinery exemption, so many process vessels may need both. Confirm your site's arrangement with the branch. One well-planned NDE campaign can serve both inspections.

What is a Mississippi serial number?

Mississippi requires every boiler and pressure vessel subject to the law to be stamped with a state serial number, in addition to the National Board registration where applicable. Include it in your vessel list so reports match state records.

How often must a vessel be inspected under API 510?

Under the current edition, external inspection is due at no more than the lesser of five years or the internal interval, and internal or on-stream inspection at no more than the lesser of half the remaining life or ten years, with special rules when remaining life is short. RBI can set other intervals.

Is Atlantis an Authorized Inspector?

No. We are not an Authorized Inspection Agency and we do not supply API-certified or state-commissioned inspectors. We provide independent NDE data for your AI and certificate inspector.

Can you inspect vessels on-stream at Pascagoula?

UT thickness, corrosion mapping, PAUT and TOFD can usually be done on-stream within the temperature limits in the procedure. Whether on-stream inspection replaces an internal entry is the AI's decision under API 510.

Who licenses industrial radiography in Mississippi?

Mississippi is an NRC Agreement State, and the Department of Health's Division of Radiological Health licenses radioactive materials, including radiography sources. RT is performed by crews licensed for work in the state.

Do you perform RBI or fitness-for-service assessments?

No. We supply the thickness data, corrosion maps and flaw sizes those assessments use; the owner's engineers or a specialist perform them.

Do you offer API 510 certification training?

No. Atlantis trains to ASNT SNT-TC-1A only. See the API inspector career guide for the certification route and NDT training in Mississippi for NDE skills.

How quickly can you mobilise to Pascagoula or Vicksburg?

We quote within 24 hours once we have the scope; the mobilisation date is agreed during scoping around your outage, permits and site access.

Next step

To line up vessel NDE that serves your AI and your certificate cycle, get a quote within 24 hours or book a scoping call. Atlantis performs the NDE; your API 510 Authorized Inspector remains inspector of record and signs the inspection report.

More Atlantis NDT services in Mississippi

• NDT training and certification in Mississippi
• Level III consulting in Mississippi
• NDT inspection services in Mississippi
• API 653 storage tank inspection support in Mississippi
• API 570 piping inspection support in Mississippi
• Practical NDT simulator in Mississippi

Part of the full range of pressure vessel inspection services from Atlantis NDT.