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How to Identify the Quality of Stainless Steel Kitchen Furniture and Equipments

Commercial kitchens serve as vital production spaces for food service operations. Their equipment endures prolonged exposure to harsh conditions—extreme heat, high humidity, severe corrosion, frequent washing, and heavy grease buildup. Consequently, the quality of stainless steel used directly determines equipment longevity, safety, hygiene standards, and maintenance costs. Throughout the kitchen system, stainless steel forms the primary structure for countertops, stoves, sinks, work stations, ventilation systems, storage units, and certain food processing machinery. However, the quality of stainless steel varies significantly. High-quality stainless steel equipment can last 10–15 years or more, while low-grade materials may rust, deform, crack, or corrode within six months, leading to substantial maintenance costs and food contamination risks.

I. Basic Knowledge of Commonly Used Stainless Steel Materials in Commercial Kitchens

1. 304 (SUS304) — The Preferred Material for Commercial Kitchens

304 stainless steel offers the following advantages:

1.1 High chromium and nickel content: Typically containing 18–20% Cr and 8–10.5% Ni, it provides exceptional corrosion resistance.

1.2 Food-grade safety: Widely used internationally in food processing equipment, sinks, dairy equipment, and more.

1.3 Excellent heat resistance: Withstands frequent heating cycles in kitchen environments.

1.4 Resistant to rust: Maintains performance even in humid, salty, or acidic/alkaline kitchen conditions.

Therefore, components in commercial kitchens that must come into direct or prolonged contact with food or water—such as countertops, sinks, steam cabinet liners, and four-door refrigerator interiors—must be constructed from 304 material.

2. 201 Stainless Steel—Low Cost but High Risk

To reduce costs, 201 grade significantly lowers nickel content—from 8% in 304 to just 1%–4%—while increasing manganese content. This results in:

– Markedly reduced corrosion resistance

-Prone to rust spots in humid environments

-Long-term use may develop spots, black marks, and pitting corrosion

-Unsuitable for food-grade environments

Many low-cost kitchen appliances fraudulently label 201 as 304, the most common form of cost-cutting deception.

3. 430 Stainless Steel—Suitable Only for Structural Components or External Applications

Key characteristics of 430 material:

-Contains chromium but virtually no nickel

-Strongly magnetic

-Moderate corrosion resistance

-Low cost  How to Identify the Quality of Stainless Steel Kitchen Furniture and Equipments

430 may be used for back panels, equipment bases, and outer casings, but is not recommended for food contact surfaces.

4. True Food-Grade Stainless Steel (304/316) vs. Cutlery-Specific Stainless Steel

316 (containing molybdenum) offers superior corrosion resistance but comes at a higher cost, making it ideal for seafood processing and ultra-corrosive kitchen environments.
For standard commercial kitchens, 304 stainless steel adequately meets food contact requirements.

II. How to Determine Stainless Steel Quality Based on Composition

1. Check the Material Test Certificate (Most Authoritative)

Reputable manufacturers will provide:

-Material Test Certificate (MTC)

-Batch number

-Chromium and nickel content specifications

-Food-grade certification or RoHS compliance report

2. Stainless Steel Identification Solution Test (Quick Method)

Commercially available 304 and 201 detection solutions are available.

Usage Instructions:

-Clean the metal surface
-Apply 1–2 drops of detection solution
-Observe color change

General Guidelines:

-304 reacts slowly or shows no color change
-201 rapidly develops color or turns black

This method facilitates on-site inspection and is commonly used by kitchen engineers.

3. Magnet Test (For Preliminary Screening Only)

Magnetic detection is not definitive, as 304 stainless steel may exhibit slight magnetism after bending or stretching.

Determination method:

Phenomenon Possible                                        Material
Non-magnetic or weakly magnetic                 304
Strongly magnetic                                              201 or 430

This method should only be used as a reference and cannot be fully relied upon.

III. Assessing Stainless Steel Quality Through Physical Indicators: Sheet Thickness is Critical

1. Standard Thickness Guidelines for Conventional Kitchen Stainless Steel Sheets

Different equipment components require varying thicknesses, with greater thickness ensuring enhanced durability:

Location ——————————Recommended Thickness
Worktop—————————— 1.2mm 304
Cooktop Surface——————— 1.5mm 304
Sink———————————– 1.2–1.5mm 304
Equipment Side Panels————– 0.8–1.0 mm
Door Panels————————— 0.8–1.0 mm
Cooktop Support Structure———- ≥1.5 mm
Drawer Slides and Support Components ≥1.0 mm

2. How to determine the authenticity of thickness?

Common shortcut methods:

-Labeled as 1.2mm, actual measurement 0.9mm  How to Identify the Quality of Stainless Steel Kitchen Furniture and Equipments

-Countertop uses laminated structure: top layer thin, bottom layer thick

-Inconsistent thickness between inner and outer panels

Inspection methods:

-Direct measurement with calipers

-Check if edges are flush

-Assess by tapping sound: thin panels produce sharp tones, thick panels sound dull

Thickness deficiency leads to:

-Countertop warping

-Bulging under heat exposure

-Sagging under load

-Cracks developing with prolonged use

IV. Assessing Stainless Steel Quality Through Craftsmanship

Even with 304-grade material, subpar craftsmanship can lead to accelerated corrosion and shortened lifespan.

1. Welding Process

High-quality welding exhibits the following characteristics:

-Uniform, full weld bead
– No cold spots or cracks
-Seamless integration with no leaks (water/air)
-No black spots or oxidation marks at stainless steel welds
-Internal welds free of burrs for easy cleaning

Causes and Hazards of Substandard Welding:

-Using ordinary steel welding rods → Creates dissimilar metal potential differences that accelerate corrosion

-Failure to acid-wash and passivate post-welding → Leads to rust spots appearing within a short time

-Rough welds → Allow food residue buildup and bacterial growth

2. Surface Finish Quality

Mainly includes:

-Brushed finish process
-Deburring treatment
-Radius processing
-Anti-fingerprint and oil-resistant surface treatment

High-quality material surfaces should exhibit:

-Uniform texture
-Resistance to water marks
-No pitting, black spots, or scratches

Substandard material surfaces often display:

-Uneven brushing (poor surface machining)
-Small black spots (high impurity content)
-Dull color (insufficient nickel content)

3. Sheet Metal Structure Design

Structural rationality impacts equipment durability:

* Are load-bearing areas reinforced?
* Does the worktop feature reinforcement plates?
* Are corners designed with rounded edges?
* Do cabinet doors utilize a double-layer structure?
* Does the main body have stable support?

Many low-cost devices reduce expenses through “thin sheet metal + no reinforcement structure,” significantly shortening their service life.

V. Assessing Material Quality Through Performance Testing

This is the most objective and practical step. Kitchen companies and chain brands commonly use the following testing methods for acceptance inspections.

1. Salt Spray Test (Corrosion Resistance Assessment)

Method:

Apply a drop of saltwater solution to the steel surface

-Leave undisturbed for 12–24 hours
-Observe for rust spots

Result Interpretation:

-304 stainless steel shows no rust spots
-201 stainless steel develops yellow rust spots or black spots

This is a highly effective testing method.How to Identify the Quality of Stainless Steel Kitchen Furniture and Equipments

2. Soy Sauce/Vinegar Immersion Test

Acidic and alkaline corrosion in the kitchen is represented by vinegar and soy sauce.

304 stainless steel remains largely unaffected.
201 stainless steel may exhibit discoloration or spotting.

3. Impact Test (Strength Check)

-Tap lightly with a rubber mallet:
-High-quality panels remain stable
-Poor-quality thin panels dent easily

4. High-Temperature Testing (Applicable to Stoves)

Inspect whether the stove top discolors, bulges, or deforms under high temperatures.
304 stainless steel is unlikely to exhibit significant discoloration, whereas thin sheets or inferior steel grades will discolor immediately.

VI. Assessing Stainless Steel Quality from a Supply Chain Perspective

1. Common Issues in the Domestic Sheet Metal Market

Common methods of cutting corners in the kitchen equipment industry include:

-201 stainless steel masquerading as 304
-Discrepancies between declared and actual thickness
-Outer panels labeled 304, inner panels made of 201
-Use of low-grade imported secondary-brand materials
-High proportion of recycled sheet metal

Identification Methods:

-Random sampling
-Requirement to review material receipt records
-On-site testing with detection solution
-Contract specification of material model and thickness

2. Differences Between Major Brands and Small Workshops

Major Brands:

-Established supply chains
-Traceable material batches
-No risk-taking through cutting corners
-Designs compliant with food service standards
-Mature welding and sheet metal fabrication techniques

Small workshops:

-Unstable material sourcing
-Frequent use of secondary brands or recycled steel
-Poor product consistency
-Rough welding, prone to leaks
-Uneven sheet metal

From a long-term cost perspective, while major brand equipment requires higher initial investment, its maintenance costs are significantly lower than those of low-cost alternatives.

VII. Commercial Kitchen Procurement Pitfall Prevention Guide

1. Must be explicitly stated in the contract:

The contract shall specify:

-All food contact surfaces must use 304 (SUS304) stainless steel
-Substitution with 201 or other materials is prohibited
-Sheet thickness must meet specified standards
-Sheet metal structures must be reinforced (where applicable)

2. Inspection Checklist for Acceptance

– Preliminary screening using a magnet
– Testing critical areas with detection solution
-Measuring thickness with calipers
– Inspecting welds and internal structure
– Randomly disassembling concealed areas to check for material skimping
– Verifying material batch numbers
– Conducting saltwater or soy sauce tests

3. Beware of Low-Price Traps

There’s an old saying in the commercial kitchen equipment industry:“You get what you pay for—cheap deals often come with hidden pitfalls.”

Common issues with low-cost equipment:

-Exterior panels: 304 stainless steel, interior panels entirely replaced with 201
-Worktops use laminated construction (0.6mm laminate over 1.0mm base)
-Racks, supports, and base plates all made of 201 stainless steel
-Polished surfaces conceal material quality, deceiving the naked eye

VIII. Examples and Analysis of Common Quality Issues in Commercial Kitchen Stainless Steel Equipment

Below are common industry problems and their causes.

1. Yellow spots appearing on countertops after six months of use

Cause: Use of 201 grade or mixed materials.
Solution: Must be replaced with 304 grade.

2. Rust forming at sink weld seams

Cause: Lack of passivation treatment or non-compliant welding materials.
Solution: Acid pickling and passivation must be performed after welding.

3. Countertop sagging or warping

Cause: Insufficient sheet thickness or lack of reinforcement structure.
Solution: Thickness ≥ 1.2mm and must include reinforcement ribs.

4. Stove countertop discoloration

Cause: Material is not heat-resistant or thickness is insufficient.
Solution: Stove countertops must use at least 1.5mm 304 stainless steel.

IX. Establishing Your Own Stainless Steel Material Acceptance Standards System

Your enterprise or kitchen engineering team can establish the following acceptance system:

1. Standardized Countertop Thickness Chart
-Clearly define thickness requirements for each type of equipment.

2. Standardized Material Specification Chart
-Specify which areas must use 304 grade and which can use 430 grade.

3. Inspection Tool Kit

-Calipers
-Testing solution
-Small magnet
-Flashlight
-Saltwater bottle  How to Identify the Quality of Stainless Steel Kitchen Furniture and Equipments
-Recording forms

4. On-site Photography and Documentation

Photograph and archive every piece of equipment during acceptance.

5. Supplier Tiering System

Tier 1 Suppliers: Traceable materials, consistent quality
Tier 2 Suppliers: Lower prices but require increased spot checks