Design Rules for Titanium Piping Systems

Design Rules for Titanium Piping Systems

Practical Engineering Rules for Reliable Corrosion-Resistant Piping

Titanium piping systems are typically selected to eliminate corrosion-related failures in seawater, brine, and aggressive chemical service.
However, titanium piping reliability depends on system design discipline—especially in flow management, crevice avoidance, galvanic isolation, fabrication control, and commissioning.

The following rules summarize field-proven practices for designing and operating titanium piping systems.

Rule 1. Define the True Service Conditions Before Selecting Grade

Titanium grade selection must be driven by the worst credible operating condition—not the average.

Confirm:

  • Medium: seawater / brine / process chemical / mixed streams

  • Temperature range (including start-up and upset)

  • Flow regime: continuous / intermittent / stagnant

  • Solids/fouling risk and cleaning method

  • “Standby” periods and preservation plan

Apply the Selection Guide only after service conditions are fully defined.

Rule 2. Treat Low-Flow and Stagnation as Primary Design Risks

Titanium relies on a stable passive film; oxygen replenishment and flow help sustain it.

Design to avoid:

  • Dead legs

  • Oversized lines operating at very low velocity

  • Long standby with liquid-filled piping

  • Low-point pockets that trap stagnant liquid

Stagnation management is corrosion management.

Rule 3. Eliminate Dead Legs and “Hidden Crevices”

Crevice conditions often occur at:

  • Socket-like geometries and sharp recesses

  • Threaded interfaces and tight gaps

  • Gasketed joints with poor compression

  • Deposits behind supports or clamps

Engineering actions:

  • Use full-bore branch design where possible

  • Minimize pockets and non-draining sections

  • Prefer designs that can be flushed and drained

Rule 4. Design for Drainability and Venting

A titanium line that cannot be drained or vented is a future maintenance problem.

Include:

  • High-point vents for air removal

  • Low-point drains for complete draining

  • Sloped lines in services prone to deposits

  • Access points for flushing and chemical cleaning

Drain/vent design is especially critical in seawater, brine, and intermittent duty.

Rule 5. Control Galvanic Coupling with Dissimilar Metals

Titanium is electrochemically noble; when coupled to less noble metals in conductive fluids, the other metal may corrode rapidly, compromising joints and interfaces.

Control measures:

  • Electrical isolation (insulating gaskets, sleeves, washers)

  • Avoid mixed-metal bolting where feasible

  • Use compatible flange strategies and isolation kits

  • Manage grounding and bonding intentionally

Galvanic control is a system responsibility, not a titanium “feature.”

Rule 6. Use Flange, Gasket, and Fastener Systems as an Engineered Set

Avoid treating sealing as a commodity detail.

Consider:

  • Gasket compatibility with the fluid and temperature

  • Compression control and bolt preload strategy

  • Creep/relaxation behavior under thermal cycling

  • Avoidance of crevice-prone gasket geometries

Practical principle:

Most leaks are joint-system problems, not pipe problems.

Rule 7. Prefer Welding Over Threads for Critical Service

Threaded joints introduce:

  • Crevices

  • Stress raisers

  • Sealant variability

  • Potential for galling and assembly damage

For corrosion-critical lines:

  • Prefer butt welds where possible

  • Use qualified procedures for titanium welding

  • If threaded connections are unavoidable, treat them as high-risk points and manage with inspection and service limits

Rule 8. Titanium Welding Must Be “Procedure-Driven”

Titanium is highly reactive when hot. Poor shielding and contamination can reduce corrosion performance.

Mandatory controls:

  • Cleanliness (oil, dust, iron contamination)

  • Full inert gas shielding during welding and cooling

  • Qualified WPS/PQR and trained welders

  • Proper purge for ID shielding (where applicable)

Engineering rule:

A great grade with poor welding behaves like a bad material.

Rule 9. Support Design Must Consider Thermal Expansion and Vibration

Titanium piping may experience significant thermal movement depending on temperature swing and layout.

Design considerations:

  • Allow for expansion loops or flexible sections

  • Avoid over-constraining supports

  • Prevent vibration in high-velocity or pump discharge sections

  • Use non-contaminating clamp materials and avoid crevice traps at supports

Rule 10. Maintain Internal Cleanliness and Prevent Cross-Contamination

Titanium is sensitive to contamination during fabrication and installation.

Controls:

  • Dedicated handling procedures

  • Avoid carbon steel tooling contact (iron pickup risk)

  • Cap ends to prevent dirt ingress

  • Clean and dry lines before commissioning

Contamination control is part of quality assurance, not housekeeping.

Rule 11. Commissioning, Preservation, and Standby Plans Must Be Defined

Many failures occur during:

  • Commissioning

  • Extended standby

  • Low-load operation

Include in design and procedures:

  • Flushing and cleaning protocol

  • Hydrotest medium quality control (as required by project)

  • Dry-out / preservation method for standby

  • Drain-and-vent strategy for long outages

Rule 12. Grade Escalation Does Not Replace Good Design

Common misconceptions:

  • “Use Grade 7 everywhere to be safe.”

  • “Higher grade fixes dead legs.”

Reality:

  • Grade escalation increases cost

  • Does not remove crevice geometry or stagnation

  • May hide the root cause in design review

Use grade escalation rationally:

Practical Review Checklist (Quick Use)

Before releasing a titanium piping design, verify:

  • No dead legs without mitigation

  • Drain/vent points included where needed

  • Galvanic isolation strategy documented

  • Flange/gasket/bolt system specified coherently

  • Welding procedures qualified and purge plan defined

  • Support/expansion analysis completed

  • Commissioning and standby preservation plan defined

How This Page Fits into the Titanium Knowledge System

This page supports and links to:

It represents the rule-based execution layer for titanium piping reliability.