When Should Refineries Use 316L Stainless Steel in Heat Exchangers?

316L stainless steel is widely used in chemical and petrochemical heat-transfer equipment, but a refinery heat exchanger cannot be specified from the grade name alone.

A process cooler handling a relatively mild hydrocarbon stream, a water-cooled chemical condenser and a refinery overhead condenser may all be described as heat exchangers, yet their corrosion environments can be fundamentally different.

Type 316L / UNS S31603 is most useful where welded fabrication is required together with greater resistance to localized corrosion than the 304 stainless steel family can provide.

Its molybdenum content improves resistance to pitting and crevice corrosion in many chloride-containing environments, while its low carbon content reduces the risk of sensitization associated with welding.

The practical purchasing question is therefore:
which exchanger components can use 316L, which ASTM product standard applies to each component, and what process data must be reviewed before the material is ordered?

Quick Answer: Where Does 316L Fit in Refinery Heat-Transfer Equipment?

Where the process-side and cooling-side environments are compatible with the alloy, Type 316L may be evaluated for:

• shell-and-tube heat exchangers
• process coolers
• chemical condensers
• selected refinery condensers
• utility coolers
• trim coolers
• selected reboiler components
• plate heat exchangers
• heat-recovery units
• chemical heating and cooling equipment

Potential 316L components include:

• shell plates
• channel covers
• heads
• heat-exchanger tubes
• tubesheets
• baffles
• tube-support plates
• nozzles
• piping connections
• flanges
• plate heat-exchanger plates

A complete heat exchanger does not necessarily use one stainless steel grade throughout.

The shell, tubes, tubesheet and piping connections can use different alloys according to pressure, temperature, corrosion conditions, mechanical design and project metallurgy.

Why Is 316L Used in Heat Exchangers and Condensers?

Type 316L is a low-carbon chromium-nickel-molybdenum austenitic stainless steel.

Its main advantages for heat-transfer equipment are:

• good general corrosion resistance in many compatible process environments
• greater localized-corrosion resistance than the 304 family in many chloride-containing environments
• good weldability
• good formability
• low carbon for reduced sensitization risk
• broad availability in plate, sheet, tube and fabricated product forms

Molybdenum and Localized Corrosion

ASTM A240 Type 316L contains 2.0–3.0% molybdenum.

Molybdenum improves resistance to pitting and crevice corrosion in many chloride-containing environments compared with the 304 stainless steel family.

This can be important in heat exchangers because chlorides may be present in:

• the process fluid
• cooling water
• wash water
• condensate
• shutdown deposits

The molybdenum addition does not make 316L immune to chlorides, seawater or chloride stress-corrosion cracking.

Low Carbon and Welded Fabrication

Type 316L has a maximum carbon content of 0.030% under ASTM A240.

The lower carbon level reduces the tendency for chromium-carbide precipitation during sensitizing thermal exposure and helps improve resistance to intergranular corrosion after welding.

This is particularly useful for:

• welded exchanger shells
• channel components
• nozzle assemblies
• pipe connections
• fabricated process coolers

Low carbon does not eliminate the need for qualified welding procedures and correct post-weld cleaning.

For a broader grade overview, review the
JISCO JUDE Austenitic Stainless Steel Guide.

316L Grade Designations and Product Standards

The purchasing rule is simple:
the grade identifies the alloy family; the product standard identifies the product being purchased.

A shell plate, heat-exchanger tube and forged flange can all belong to the 316L family while requiring completely different ASTM specifications.

ASTM A240 Type 316L / UNS S31603 Chemical Composition

The following values are ASTM A240 specification limits for Type 316L flat products. They should not be described as a producer’s typical heat chemistry.

Producer datasheets may publish typical chemistry near the middle of these ranges, but delivered material should be accepted against the governing standard, mill test certificate and project specification.

Which Heat Exchanger Components Use 316L?

1. Shells and Channel Components

ASTM A240 Type 316L plate may be used for selected shells, channels, covers and fabricated heads where the process environment and design code permit the alloy.

A shell-plate inquiry should normally define:

• thickness
• width
• length
• surface condition
• flatness requirement
• pressure-vessel specification
• NDE requirements where applicable
• heat-number traceability

JISCO JUDE publishes
hot-rolled stainless steel sheet and plate
for applications including large tanks and heat exchangers.

2. Seamless Heat-Exchanger Tubes

ASTM A213/A213M TP316L may be specified where the exchanger requires seamless austenitic heat-exchanger tubing.

A tube RFQ should identify:

• grade
• ASTM standard
• outside diameter
• minimum or average wall thickness
• tube length
• heat-treatment condition
• NDE requirement
• hydrostatic testing where specified
• surface requirement

JISCO JUDE’s
Stainless Steel Tube & Pipe page
lists ASTM A213 heat-exchanger tubing together with available tube and pipe supply-reference ranges.

3. Welded Heat-Exchanger and Condenser Tubes

ASTM A249/A249M covers welded austenitic tubes intended for boiler, heat-exchanger and condenser service.

TP316L welded tubing may be suitable when permitted by the heat-exchanger design and project specification.

The RFQ should confirm:

• welded construction
• OD
• wall thickness
• length
• heat treatment
• mechanical testing
• NDE
• surface condition
• supplementary project requirements

The phrase “316L stainless tube” is not sufficient for an engineered refinery purchase.

4. Tubesheets

Tubesheets require more careful specification than ordinary flat sheet because they carry tubes, pressure loads and tube-to-tubesheet joints.

Depending on the exchanger design and construction code, a 316L tubesheet may be produced from:

• plate
• forging
• clad material
• another project-approved product form

Do not automatically specify ASTM A240 simply because a finished tubesheet has a flat shape.

The engineering drawing should control:

• material specification
• thickness
• corrosion allowance
• tube-hole diameter
• tube pitch
• tube-joint design
• cladding requirement where applicable

5. Baffles and Tube-Support Plates

316L sheet or plate may be used for baffles and support plates where the shell-side corrosion environment requires stainless construction.

Important manufacturing requirements may include:

• plate thickness
• flatness
• hole diameter
• hole position
• cutting tolerance
• surface condition

For drawing-based flat components, JISCO JUDE’s
cutting, slitting and cut-to-length service
can be reviewed according to the required dimensions and tolerance.

6. Nozzles and Process Connections

Heat-exchanger nozzles are normally specified as piping products rather than simply cut from plate.

Possible 316L-family components include:

• ASTM A312 TP316L nozzle pipe
• ASTM A403 WP316L elbows or reducers
• ASTM A182 F316L forged flanges

These specifications should not be replaced by ASTM A240 simply because all components use a 316L-family chemistry.

7. Plate Heat-Exchanger Plates

Plate heat exchangers use thin formed plates instead of a conventional shell-and-tube bundle.

Cold-rolled 316L sheet or coil may be used as raw material in selected designs.

Manufacturers may require tight control of:

• sheet thickness
• thickness tolerance
• surface quality
• flatness
• forming consistency
• coil or sheet width

JISCO JUDE publishes
cold-rolled stainless steel sheet and coil
for petroleum, petrochemical and other industrial applications.

8. Flanges and Wrought Fittings

A heat-exchanger package may also require:

• weld-neck flanges
• blind flanges
• elbows
• tees
• reducers
• forged pressure parts

Where Type 316L is required, the component specification should match the manufacturing route:

• ASTM A403 WP316L for applicable wrought fittings
• ASTM A182 F316L for applicable forged flanges and pressure components

Component-to-Raw-Material Procurement Matrix

ASTM A213 vs A249 vs A269 vs A312

ASTM A213

ASTM A213 covers seamless ferritic and austenitic alloy-steel boiler, superheater and heat-exchanger tubes.

It is a common specification when seamless TP316L exchanger tubing is required.

ASTM A249

ASTM A249 covers welded and heavily cold-worked welded austenitic tubes intended for boiler, heat-exchanger and condenser service.

Use it where the project specification permits welded TP316L exchanger tubing.

ASTM A269

ASTM A269 covers seamless and welded austenitic stainless steel tubing for general corrosion-resisting and temperature service.

It should not automatically replace A213 or A249 when the engineering specification requires a dedicated heat-exchanger tube standard.

ASTM A312

ASTM A312 covers austenitic stainless steel process pipe.

It is commonly relevant to exchanger nozzles and external process piping rather than conventional exchanger tube bundles.

Procurement rule:
do not select the ASTM standard from the stainless steel grade alone.

Why Must Both the Process Side and Cooling Side Be Reviewed?

A heat exchanger contains at least two fluid environments.

A grade may perform well against the process stream while being unsuitable for the cooling medium.

Material review should include:

• process-side fluid
• process concentration
• process temperature
• cooling-water chemistry
• chloride concentration
• pH
• oxygen content
• flow velocity
• deposits
• shutdown conditions
• cleaning chemistry

For some exchangers, cooling water rather than the process fluid becomes the controlling corrosion environment.

Chloride Concentration, Temperature and Crevices

316L provides more resistance to localized corrosion than the 304 stainless steel family in many chloride environments, but chloride concentration cannot be reviewed by itself.

Pitting and crevice-corrosion risk generally increases with:

• increasing chloride concentration
• increasing temperature
• stagnant conditions
• deposits
• tight crevices
• poor surface condition

A low-temperature dilute chloride stream and a hot stagnant chloride-containing exchanger are therefore different material-selection problems.

Is 316L Suitable for Refinery Overhead Condensers?

316L should not be treated as the default material for refinery overhead condensation service.

Some refinery overhead environments can contain chloride-bearing and acidic condensates that are significantly more aggressive than ordinary process water.

Material selection should consider:

• chloride loading
• water dew point
• acid formation
• temperature profile
• H2S and sulfur compounds
• deposit chemistry
• startup and shutdown conditions
• project corrosion study

Where the refinery metallurgy specification requires a higher-alloy material, 316L should not be substituted simply because it contains molybdenum.

Can 316L Be Used for Seawater-Cooled Exchangers?

316L should not be marketed as a universally suitable seawater heat-exchanger material.

Warm seawater, chlorination, stagnant zones, tube-to-tubesheet crevices and deposits can create localized-corrosion conditions beyond the reliable design range of conventional 316L.

Depending on the project, engineers may evaluate:

• duplex 2205
• super duplex stainless steel
• 6Mo stainless steel
• titanium
• other corrosion-resistant alloys

The correct choice depends on seawater temperature, chlorination, velocity, exchanger geometry, fabrication and lifecycle cost.

For higher-chloride stainless steel families, see the
JISCO JUDE Duplex Stainless Steel Guide
and
Super Austenitic Stainless Steel Guide.

Chloride Stress-Corrosion Cracking

316L is a conventional austenitic stainless steel and can remain susceptible to chloride stress-corrosion cracking under sufficiently aggressive combinations of chloride exposure, tensile stress and temperature.

The molybdenum addition improves resistance to localized corrosion but does not make 316L immune to chloride SCC.

Where SCC becomes a controlling design mechanism, duplex stainless steel or another project-approved material may provide advantages.

Welding, Heat Tint and Post-Weld Cleaning

The low carbon level of 316L improves resistance to sensitization, but fabrication quality still affects final corrosion performance.

Welded exchanger components may require control of:

• weld procedure
• heat input
• interpass temperature
• shielding
• joint cleanliness
• iron contamination
• heat tint
• post-weld cleaning

Depending on the project specification, post-fabrication treatment may include mechanical cleaning, pickling, passivation and final surface inspection.

When Is 316L Not Enough?

Another alloy should be evaluated when the exchanger operates in service such as:

• hot concentrated chloride solutions
• severe seawater cooling
• aggressive refinery overhead condensate
• strong hydrochloric-acid environments
• severe chloride SCC conditions
• highly aggressive sour service
• high-temperature corrosion mechanisms outside the practical range of 316L

Possible alternatives depend on the damage mechanism and may include:

• duplex 2205
• super duplex 2507
• 904L
• 6Mo austenitic stainless steel
• titanium
• nickel-base alloys

A higher-alloy material is not automatically the most economical solution. Alloy selection should compare corrosion risk, fabrication requirements, design code, expected service life and total lifecycle cost.

304L vs 316L vs 2205 vs Higher-Alloy Materials

What Should a 316L Heat-Exchanger RFQ Include?

1. Equipment: shell-and-tube exchanger, condenser, cooler or plate exchanger.
2. Component: shell, tube, tubesheet, baffle, nozzle, flange or another part.
3. Grade: Type 316L / UNS S31603.
4. Product standard: ASTM A240, A213, A249, A269, A312, A403 or A182 as applicable.
5. Process-side fluid: actual chemical or hydrocarbon stream.
6. Process concentration: where relevant.
7. Process temperature: normal and design values.
8. Cooling medium: cooling water, closed-loop water, air, seawater or other medium.
9. Cooling-water chloride: where relevant.
10. pH: where known.
11. H2S / sulfur compounds: where relevant.
12. Operating and design pressure: where applicable.
13. Tube OD and wall thickness: for exchanger tubing.
14. Tube length: straight or U-tube requirements.
15. Plate dimensions: thickness, width and length.
16. Surface requirement: where applicable.
17. Welding requirement: project WPS or fabrication requirement.
18. NDE / testing: hydrostatic, eddy-current, UT, PT or other project inspection.
19. Certification: MTC / EN 10204 requirement.
20. Quantity: pieces, meters or tonnage.
21. Drawing: exchanger or component drawing.
22. Destination: country, port and delivery schedule.

Example 316L Heat-Exchanger Material RFQ

Providing both process-side and cooling-side data gives the material supplier much more useful information than requesting only “316L heat-exchanger material.”

Incoming Inspection and Documentation

Depending on the project specification, incoming inspection may include:

• heat-number traceability
• mill test certificate
• UNS S31603 / TP316L grade confirmation
• carbon content
• molybdenum content
• chemical composition
• mechanical properties
• plate thickness and dimensions
• tube OD and wall thickness
• surface condition
• PMI where specified
• hydrostatic or NDE requirements
• project-specific supplementary testing

Inspection requirements should be applied according to the project rather than automatically added to every 316L order.

JISCO JUDE’s quality-management information can be reviewed on the
Quality Management page.

How JISCO JUDE Supports Heat-Exchanger Manufacturers

JISCO JUDE supplies stainless steel flat products and tubular products for petrochemical, chemical and industrial equipment manufacturing.

Relevant product categories include:

• hot-rolled stainless steel sheet and plate
• cold-rolled stainless steel sheet and coil
• stainless steel seamless and welded tube / pipe
• cutting, slitting and cut-to-length services

Frequently Asked Questions

Should I specify ASTM A213 or ASTM A249 for 316L heat-exchanger tubes?

ASTM A213 is commonly used for seamless heat-exchanger tubing, while ASTM A249 covers welded heat-exchanger and condenser tubing. The equipment drawing and project specification should control the final choice.

Can ASTM A269 replace ASTM A213?

Not automatically. ASTM A269 is a general-service tubing specification, while ASTM A213 is specifically intended for boiler, superheater and heat-exchanger tubes. Use the standard required by the exchanger design and purchase specification.

Is 316L suitable for refinery overhead condensers?

Not as a general rule. Refinery overhead condensates can contain chlorides, acidic species and sulfur compounds. Final metallurgy should follow the actual process chemistry and refinery corrosion study.

Can 316L be used in seawater-cooled heat exchangers?

316L should not be assumed to be suitable for all seawater cooling. Warm seawater, chlorination, deposits and crevices can create severe localized-corrosion conditions that require duplex, super duplex, titanium or another corrosion-resistant material.

Can the shell and tubes use different alloys?

Yes. Heat-exchanger components may use different materials when the process side, cooling side, temperature, pressure and mechanical requirements justify different alloy selections.

What standard should be used for a 316L tubesheet?

There is no universal answer based only on the words “316L tubesheet.” Depending on the design, the tubesheet may be manufactured from plate, forging, clad material or another project-approved product form. The engineering drawing and pressure-equipment specification should define the permitted material standard.

Why does temperature matter with chloride-containing cooling water?

Localized-corrosion and stress-corrosion-cracking risks can increase as chloride concentration, temperature, deposits and crevice severity increase. Chloride concentration should therefore be reviewed together with operating temperature and exchanger geometry.

What should I send JISCO JUDE for a 316L heat-exchanger quotation?

Send the exchanger drawing, component list, grade, ASTM specification, plate or tube dimensions, process-side fluid, cooling-side fluid, chloride concentration, temperature, pressure, testing requirements, certification, quantity and delivery destination.

Request 316L Material for Heat Exchanger Manufacturing

Technical note:
This guide is intended for preliminary raw-material screening and procurement. Final material selection for refinery, petroleum and chemical heat-transfer equipment should follow the actual process chemistry, cooling medium, chloride concentration, temperature, pressure, corrosion mechanism, design code and project metallurgy specification.