Cleaning and maintenance of stainless steel bellows: removal and prevention of scale and green rust

1. Causes of Scale and Green Rust on Stainless Steel Plumbing Bellows

Scale (Calcium Carbonate Deposits)

Source: Hard water areas (high calcium and magnesium ion content), which crystallize upon heating.

Damage: Narrower pipe diameter → Reduced water flow and decreased heat exchange efficiency.

Green Rust (Verdigris/Basic Copper Carbonate)

Source: Reaction of copper connectors with moisture and oxygen (commonly found at copper-stainless steel interfaces).

Damage: Corrosion of gaskets, leading to leaks.

2. Cleaning Methods (Select by Contamination Type)

Scale Removal Method

① White Vinegar Soaking Method (Mild Scale)

Steps:

Remove the bellows and rinse the interior with clean water to remove impurities.

Pour in a 1:1 solution of white vinegar and water and let it sit for 2 hours.

Gently scrub the interior with a soft-bristled brush until the vinegar odor is gone.

② Citric Acid Dissolution Method (Severe Scale)

Steps:

Add 20g of food-grade citric acid per liter of warm water (50°C) and pour into the pipe.

Soak for 4-6 hours (extend to 12 hours for stubborn scale).

Flush with a high-pressure water gun (pressure ≤ 0.3MPa).

Note: Do not use hydrochloric acid or toilet cleaners (they corrode the passivation layer of stainless steel).

Rinse thoroughly after cleaning to avoid acid residue.

Green Rust Removal Method

① Baking Soda Paste (Surface Green Rust)

Steps:

Mix baking soda and water into a paste and apply to the rusted area.

Gently scrub with an old toothbrush and rinse with clean water.

② Specialized Patina Cleaner (Stubborn Patina)

How to Use:

Choose a patina cleaner containing benzotriazole.

After spraying, let it sit for 5 minutes, then buff with a cotton cloth.

Note: Wear gloves when handling and avoid contact with skin.

After cleaning, apply a small amount of petroleum jelly to prevent oxidation.

3. Preventive Measures (Long-Term Solution)

Inhibit Scale Formation

Install a magnetized water treatment system: This changes the structure of calcium and magnesium ions and reduces crystallization.

Drain pipes regularly: Flush them monthly (especially for floor heating systems).

Prevent Green Rust

Apply sealant to joints: Choose a waterproofing paste containing polytetrafluoroethylene (PTFE).

Replace compatible accessories: Use stainless steel bellows with stainless steel connectors to avoid direct copper-stainless steel contact.

Routine Maintenance Recommendations

4. FAQ about stainless steel plumbing bellows

• Can corrugated pipe be bent? Will this shorten its lifespan?

Bending Specifications:

Minimum bend radius ≥ 3 times the pipe diameter (e.g., DN20 pipe requires a minimum bend radius of 60mm).

Do not bend at sharp angles (sharp bends can cause metal fatigue cracking).

• Why is the bellows leaking at the joints?

Common Causes:

Deterioration of the gasket (it is recommended to replace the silicone gasket every 3 years).

Misaligned threads (during installation, tighten manually and then tighten with a wrench 1/4 turn).

• What water pressure can bellows withstand?

Pressure Standards:

Household Type: 1.6MPa~2.5MPa (National Standard).

Gas-only Type: ≥4MPa (must have armor).

• How to Identify Low-Quality Bellows?

Trap Guide:

Inspect the welds: High-quality pipes have even, burr-free welds, while low-quality pipes have rough welds.

Measure Thickness: Use a caliper. Be cautious if the wall thickness is less than 0.3mm. Check the certification: Look for the "GB/T 14525-2010" standard.

• Does the bellows need to be replaced regularly?

Replacement recommendations:

Normal water quality: 5-8 years (even if there is no visible damage).

Hard water/high temperature water: 3-5 years (scale accelerates aging).