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2026 Statistics

Key Facts: CSWIP 3.1U Exam

5 Years

Certification Validity Period

CSWIP Certification Document

70%

Minimum Passing Grade

TWI CSWIP 3.1U Syllabus Specification

-800 mV

Steel Protection Threshold (Ag/AgCl)

DNV-RP-B401 / CSWIP CP Manual

CSWIP 3.1U certification qualifies commercial divers to carry out subsea NDT inspections, including visual, underwater MPI, ultrasonic thickness measuring, and cathodic protection potential reading. This 100-question practice bank covers theoretical principles, calibration rules, and CSWIP reporting standards.

Sample CSWIP 3.1U Practice Questions

Try these sample questions to test your CSWIP 3.1U exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1What is the primary objective of performing a preliminary subsea visual inspection (General Visual Inspection / GVI) on an offshore jacket structure?

A.To assess overall structural integrity, detect major mechanical damage, and locate gross marine fouling.

B.To detect subsurface micro-cracking inside structural tubular members.

C.To measure exact sound velocity variations across welded nodal joints.

D.To measure internal wall loss without cleaning surface deposits.

Explanation: A General Visual Inspection (GVI) provides a broad overview of the subsea structure to identify gross structural damage, missing members, impact damage, bent bracing, debris, and overall marine growth coverage before close visual or NDT testing.

2How does Close Visual Inspection (CVI) differ from General Visual Inspection (GVI) during a CSWIP 3.1U subsea survey?

A.CVI is conducted entirely using ROVs without diver intervention.

B.CVI requires localized surface cleaning down to bare metal or tight marine growth removal to examine specific details and welds.

C.CVI is restricted to top-side splash zone structural members only.

D.CVI replaces all non-destructive magnetic and ultrasonic testing requirements.

Explanation: Close Visual Inspection (CVI) is a detailed inspection of specific areas (such as welded nodes or suspected defect zones) that requires cleaning the surface of marine growth and corrosion products so surface features, pitting, and weld profiles can be scrutinized at close distance.

3Which surface cleaning tool is most appropriate for removing heavy hard marine growth (such as thick barnacles and tubeworms) prior to CVI and MPI without gouging the underlying steel weld?

A.Heavy oxy-arc cutting torches

B.Coarse angle grinding discs removing 3 mm of parent plate

C.Hydraulic wire brushes or needle scalers used with controlled pressure

D.High-explosive micro-detonation cords

Explanation: Hydraulic wire brushes and pneumatic/hydraulic needle scalers effectively dislodge hard marine fouling while preserving the steel surface profile when operated correctly by an inspection diver.

4When inspecting a subsea structural tubular weld, what visual appearance distinguishes a fatigue crack from a superficial surface scratch?

A.A fatigue crack is always perfectly straight and perfectly perpendicular to the water surface.

B.A scratch always exhibits rust staining while a fatigue crack remains shiny steel underwater.

C.A fatigue crack only forms inside internal structural air pockets.

D.A fatigue crack typically follows stress concentrations at the weld toe, showing depth and sharp linear progression, whereas a scratch has rounded mechanical edges.

Explanation: Fatigue cracks initiate at stress concentration points such as weld toes, exhibiting sharp propagation paths and measurable depth, whereas mechanical scratches display smooth gouged contours caused by external tool or wire rope contact.

5What surface preparation cleanliness standard (equivalent to ISO 8501-1) is required before conducting underwater magnetic particle inspection (MPI) on structural steel welds?

A.Sa 2.5 / Very thorough blast cleaning to bright metal

B.Sa 1 / Light brush cleaning leaving loose scale

C.St 2 / Hand tool scraping leaving firmly adhering paint

D.No cleaning is required prior to subsea MPI

Explanation: Subsea MPI requires a high level of cleanliness (equivalent to Sa 2.5 bright metal finish) across the weld cap and at least 50 mm of adjacent parent metal to ensure magnetic particles move freely and form clear crack indications.

6In subsea structural inspection, what is 'weld undercut'?

A.Excess reinforcement metal deposited on the top cap of a butt joint.

B.A groove melted into the parent metal adjacent to the weld toe or root that has not been filled by weld metal.

C.Internal gas trapped in the center of the weld metal pool.

D.An intentional drainage slot cut through structural tubular joints.

Explanation: Undercut is a sharp groove melted into the base metal along the toe or root edge of a weld bead left unfilled by weld deposit, creating a significant stress raiser.

7Why must an inspection diver visually examine the splash zone of a fixed offshore platform with special care?

A.The splash zone is completely shielded from marine growth and cathodic protection currents.

B.Cathodic protection systems operate with double efficiency in the splash zone.

C.The splash zone experiences high oxygenation, wave action, cyclic wetting/drying, and severe corrosion and fatigue rates.

D.Steel in the splash zone is immune to pitting and stress corrosion cracking.

Explanation: The splash zone combines abundant dissolved oxygen, mechanical wave impact, and alternating wet/dry conditions where cathodic protection is ineffective during dry cycles, making it highly vulnerable to accelerated corrosion and fatigue.

8Which instrument is used by an underwater visual inspector to measure the depth of pitting corrosion on a steel plate?

A.An ultrasonic flaw detector set to shear wave mode

B.A high-frequency eddy current phase angle meter

C.A optical refractometer

D.A dial-gauge or needle-point pit depth gauge

Explanation: A mechanical needle-point pit depth gauge (or specialized diver dial indicator) measures the physical depth from the uncorroded reference surface down to the base of the corrosion pit.

9What is the primary visual indicator of galvanic corrosion on a subsea steel structure near a bronze valve?

A.Accelerated metal loss and heavy rust scale on the steel adjacent to the bronze joint.

B.Severe pitting on the bronze valve body while the steel remains unattacked.

C.Formation of thick white calcium carbonate scales on the copper alloy only.

D.Discoloration of seawater into a deep purple hue.

Explanation: In a galvanic couple between steel (more anodic) and bronze (more cathodic) in seawater, the steel corrodes preferentially at an accelerated rate near the junction.

10Which visual defect term describes a localized depression on a tubular member caused by an external mechanical blow or collision?

A.Lamination

B.Dent

C.Porosity

D.Inclusion

Explanation: A dent is a permanent mechanical deformation of a tubular wall profile caused by impact from supply vessels, dropped objects, or anchor cables.

About the CSWIP 3.1U Exam

CSWIP 3.1U Underwater Inspection Diver certification is the international benchmark for commercial divers conducting non-destructive testing (NDT) on offshore oil & gas platforms, subsea pipelines, and marine structures. The examination evaluates competence in subsea visual inspection, magnetic particle inspection (MPI), ultrasonic digital thickness measurement (UT), cathodic protection (CP) potential probing, subsea photography/video, marine growth assessment, and CSWIP reporting standards.

Questions

100 scored questions

Time Limit

2 hours for theoretical papers (self-paced practice)

Passing Score

70%

Exam Fee

£1,800 - £2,400 (TWI Certification Ltd (CSWIP))

CSWIP 3.1U Exam Content Outline

20%

Underwater Visual Inspection & Subsea Cleaning

Visual inspection methodology, marine growth classification, surface preparation techniques (grit blasting, needle gunning), and structural defect assessment.

20%

Magnetic Particle Inspection (MPI) Underwater

Subsea electromagnetic and permanent magnet yokes, fluorescent/black magnetic ink delivery systems, ultraviolet illumination, and weld defect identification.

20%

Ultrasonic Thickness Measurement & Eddy Current Testing

Digital UT pulse-echo meters, compression wave transducers, calibration blocks, velocity matching, coating thickness compensation, and subsea ECT methods.

20%

Cathodic Protection Potential & Subsea Corrosion

Ag/AgCl reference cell potential probes, calibration procedures, protection potential thresholds (-800 mV to -1050 mV), anode consumption, and corrosion mechanisms.

20%

Photography, Video Recording & CSWIP Reporting/Safety

Underwater close-up camera setup, scale rules, video log records, daily dive inspection sheets, CSWIP document control, and diver NDT safety.

How to Pass the CSWIP 3.1U Exam

What You Need to Know

Passing score: 70%
Exam length: 100 questions
Time limit: 2 hours for theoretical papers (self-paced practice)
Exam fee: £1,800 - £2,400

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

CSWIP 3.1U Study Tips from Top Performers

1Memorize cathodic protection potential thresholds: -800 mV to -1050 mV for steel relative to Ag/AgCl reference electrodes in seawater.

2Understand sound velocity calibration in steel (~5920 m/s) and transducer selection for pitted or corroded subsea surfaces.

3Master magnetic particle ink concentrations, pole spacing, field strength verification using pie gauges or flux indicators, and UV light intensity requirements.

Frequently Asked Questions

What prerequisites are required to sit the CSWIP 3.1U exam?

Candidates must hold a valid HSE Part 1 / Commercial Surface-Supplied Air Diver qualification (or equivalent IMCA recognised qualification) and an up-to-date commercial diving medical certificate before attending the course and exam.

What NDT methods are covered under CSWIP 3.1U?

CSWIP 3.1U covers visual inspection, subsea magnetic particle inspection (MPI), ultrasonic thickness measurement (UT), cathodic protection (CP) potential measurement, close-up photography, and CCTV video recording.

How long is CSWIP 3.1U certification valid?

CSWIP 3.1U certification is valid for 5 years, subject to continuous dive inspection logging and recertification examination at the end of the 5-year cycle.

100+ Free CSWIP 3.1U Practice Questions

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