Sheath Material

Features

Advantages

Disvantages

Typical Applications

SS304/321

The most common economical type

Good oxidation resistance (up to about 870°C), good forming and welding properties

Average corrosion resistance,  poor performance in reducing atmospheres (such as cracking furnaces, carburizing)

General industrial furnaces (no strong corrosion, no chloride ions), hot water systems, heating systems, non-critical process temperature measurement (<870°C oxidizing atmosphere)

SS316/316Ti

Better corrosion resistance than 304/321 is required, especially in chloride ion environment

SS316:significantly improved corrosion resistance due to add molybdenum SS316Ti:adding titanium (Ti) for stabilization treatment to improve high temperature sensitization issues

Costs more than 304/321.

Chloride ion stress corrosion cracking may still occur (although better than 304/321).

Does not perform well in high temperature reducing atmospheres (carburizing, sulfiding)

Chemical processes (containing weak acids, chloride ions), food processing, pharmaceuticals, low-temperature sections of flue gas desulfurization (FGD), general petrochemical applications

SS310

Stainless steels that require higher high temperature oxidation resistance

The continuous use temperature in an oxidizing atmosphere can reach about 1150°C

Very sensitive to sulfide corrosion (such as H₂S), and problems in the presence of chloride ions at high temperatures

High temperature air/oxidizing atmosphere furnaces (such as heat treatment furnaces, ceramic kilns, high temperature sections of incinerators), radiant tubes

SS446

Ferritic stainless steel specifically for use in sulfur-containing environments (high temperature resistance to sulfurization)

Excellent resistance to high temperature sulfidation corrosion,

Good oxidation resistance,

Low thermal expansion coefficient

Poor toughness, difficult to process

May become brittle when used for a long time at >480°C.

Poor resistance to chloride ion corrosion.

Sulfur-containing fuel combustion environment (such as refinery heating furnace, cracking furnace, coal gasification furnace), garbage incinerator and other sulfur-containing high-temperature reducing atmospheres

SS347

Good high temperature stability and intergranular corrosion resistance are required

Stabilized by adding niobium (Nb),

Good high temperature oxidation resistance,

High temperature strength is better than 304/316

The cost is higher than 304/316, and it still has limitations in strong reducing atmospheres and chloride ion-containing environments.

Aircraft engine parts, heat exchanger tubes, equipment that needs to be used at high temperatures after welding, industrial furnaces that require high temperature stability (no strong corrosion)

Inconel600

General nickel-based alloy, used in high temperature, strong redox alternation or weak corrosion environment

Excellent high temperature oxidation resistance: up to about 1150°C.

Good high temperature strength.

Excellent resistance to chloride ion stress corrosion cracking.

Relatively stable in carburizing/nitriding atmospheres.

Poor resistance to reducing sulfur corrosion: Sensitive to H₂S, etc.

Not resistant to strong acids (such as hot concentrated sulfuric acid, hydrochloric acid).

The cost is much higher than stainless steel.

Heat treatment furnaces (especially carburizing, carbonitriding), nuclear industry (steam generator tubes), petrochemical cracking furnaces (sulfur-free or low-sulfur), ammonia reformers, electronic components, aerospace

Inconel625

Harsh environments requiring extremely excellent corrosion resistance and ultra-high strength

Excellent resistance to general and localized corrosion,

Excellent high temperature strength,

Good oxidation resistance: up to about 1150°C,

Good resistance to stress corrosion cracking.

One of the most expensive commonsheath materials

Offshore platforms, seawater/brine cooling systems, strong acid environments (such as hydrometallurgy, chemical plants), flue gas desulfurization (FGD) high temperature corrosion areas, aerospace high temperature components, nuclear waste treatment, extremely corrosive chemical processes

Inconel800

Where a balance of high temperature strength, carburization resistance and good redox corrosion resistance is required

Excellent resistance to high temperature carburization and oxidation,

Good resistance to high temperature corrosion:

Not as good as higher grade alloys in strong reducing sulfur corrosion or strong acidic environment

Ethylene cracking furnace tubes (anti-carburization), heat treatment furnaces (carburization, controlled atmosphere), petrochemical heating furnaces, industrial gas turbines, heat exchangers, chemical reactors (high temperature corrosion)

Inconel825

Specially designed for harsh environments with strong reducing acids (especially sulfuric acid and phosphoric acid) and resistance to stress corrosion cracking

Outstanding resistance to strong reducing acid corrosion

Excellent resistance to stress corrosion cracking

Good resistance to pitting and crevice corrosion.

Good oxidation resistance (approximately 1000°C)

High cost, high temperature strength is not as good as 625/800

Sulfuric acid pickling equipment, phosphoric acid production, offshore oil production, nuclear fuel reprocessing, chemical strong acid environment, flue gas desulfurization (FGD) absorption tower

Nicrobell

High nickel content (>70%), soft texture, good sealing, but lower strength than Inconel

High temperature and oxidation resistance, reducing atmosphere resistance,

not resistant to chloride ions

High cost

Heating furnace, annealing furnace (≤1200℃), reactor (non-strongly corrosive media), pipeline temperature monitoring, gas turbine, steam pipeline, glass furnace low temperature section (≤1300℃)

Type

Temperature range

Advantages

Disadvantages

K

-40-1200C

Good thermoelectric potential linearity and moderate sensitivity;

Strong oxidation resistance, suitable for oxidizing or inert atmosphere;

Low price, most widely used in industry

Easy to corrode in reducing atmosphere (such as sulfur, carbon, vacuum), and has poor low temperature accuracy.

J

-40-750C

Fast response speed: suitable for measuring rapid temperature changes.

Limited temperature range: Applicable from -40°C to 750°C.

Oxidation issues: Performs poorly in high temperature oxidizing environments

T

-40-350C

Excellent low temperature performance, good stability, suitable for humid or low oxygen environment

Not suitable for high temperature measurements and has a limited service life

E

-40-900C

High sensitivity,

Good low temperature performance

Not suitable for strong acid environment

N

-40-1200C

High temperature stability,

Strong oxidation resistance

Lower sensitivity:

S

0-1600C

High precision,Good stability

Extremely high cost,

low response speed

No

Qualifications and manufacturing capabilities

1

Valid quality management system certifications

2

Certifications for specific industries or safety requirements

3

Raw material and finished product tests ,such as composition analysis, metallography, tensile test, insulation resistance test, voltage withstand test, thermal cycle test, precision test)

4

Modern drawing, filling, rolling and other production equipment, the equipment has good precision and stability

5

The production process is controlled, and key processes (such as powder filling density control, annealing process, end sealing) have clear operating instructions and records

6

Complete process of incoming material inspection (Incoming QC), process inspection (IPQC), and final inspection (FQC)

7

Perfect batch traceability system (from raw materials to finished products), complete production batch records

8

Complete defective product handling

No

Price and Cost

1

Competitive prices and clear trade terms (FOB, CIF, DDP, etc.)

2

ReasonableMOQ reasonable and flexible for small trial orders or customized specifications

3

Paymentterms (such as T/T, L/C) and conditions (such as deposit ratio, final payment ) are negotiable and risks are controllable

4

Not only the price is considered, but also the long-term cost benefits brought by quality reliability, service life, maintenance cost, etc. Low price but high failure rate will result in higher total cost

No

Delivery time and supply chain reliability

1

Production time meets industry standards

2

On-time delivery, with a high historical delivery on-time rate

3

Sufficient production capacity to cope with order fluctuations and the ability to process expedited orders quickly

4

The supply of key raw materials (such asthermocouplealloy wires and high-purity magnesium oxide) is stable, and there are plans to deal with supply chain disruptions

No

Communication and customer service

1

Sales and technical support staff can communicate effectively in fluent English (or other customer languages), and technical documents (specifications, test reports, certificates, operating manuals) are in English

2

Prompt and professional response to inquiries, emails, and technical issues

3

Sufficient technical capabilities to help customers select models, solve application problems, and provide customized suggestions

4

Provide complete, clear and compliant export documents (such as commercial invoice, packing list, bill of lading, certificate of origin, test report, material certification, declaration of conformity, etc.)

No

Quality Assurance and After-Sales Service

1

The warranty terms are clear and reasonable

2

The response speed and solution are satisfactory when quality disputes arise

3

Clear return and claims policies and procedures