The material system for reducers is identical to that for tees and elbows. Selection is mainly based on the conveyed medium (corrosiveness, temperature, pressure) and service environment (industrial/civil, buried/aboveground). Materials are primarily divided into two categories: metallic and non-metallic. The detailed classification and applicable scenarios are as follows:
I. Metallic Reducers
(Mainstream in industry, suitable for high pressure, high temperature and corrosive media)
1. Carbon Steel
- Common grades:
- GB: 20# steel, Q235B, 16Mn (Q345R);
- ASME: ASTM A234 WPB, ASTM A105 (forged small size).
- Key properties: low cost, high strength, good weldability, temperature resistance ≤ 450℃.
- Application scenarios: non-corrosive water, oil, natural gas and steam pipelines (e.g., municipal water supply networks, long-distance oil pipelines, HVAC pipelines).
- Typical specifications: DN15~DN1200, PN0.6~PN40.0 (medium and high-pressure industrial pipelines).
2. Stainless Steel
- Common grades:
- GB: 06Cr19Ni10 (304), 022Cr17Ni12Mo2 (316L);
- ASME: ASTM A403 WP304, WP316L.
- Key properties: corrosion resistant (acid, alkali, seawater, chloride ions), high temperature resistance ≤ 800℃, hygienic grade (polishable).
- Application scenarios:
- Chemical pipelines for acidic and alkaline media (e.g., sulfuric acid, caustic soda);
- Food and pharmaceutical hygienic pipelines (e.g., drinking water, liquid medicine);
- offshore engineering and coastal pipelines (seawater corrosion resistance).
- Typical specifications: DN15~DN600, PN0.6~PN25.0 (medium and high-pressure corrosion-resistant pipelines).
3. Alloy Steel
- Common grades:
- GB: 12Cr1MoVG, 15CrMoG;
- ASME: ASTM A234 WP11, WP22.
- Key properties: high temperature resistance ≤ 550℃, high pressure resistance (PN≥10.0MPa), creep resistance.
- Application scenarios: main steam pipelines of power plant boilers, high-temperature and high-pressure chemical process pipelines (e.g., cracking furnace steam pipelines).
- Typical specifications: DN50~DN300, PN10.0~PN40.0 (ultra-high pressure and high-temperature pipelines).
4. Cast Iron / Ductile Iron
- Common grades: Gray Iron HT200, Ductile Iron QT450-10.
- Key properties: extremely low cost, good castability, high brittleness, low pressure resistance (PN≤1.6MPa).
- Application scenarios: low-pressure gravity flow pipelines (e.g., drainage in old buildings, farmland irrigation pipelines).
- Typical specifications: DN50~DN1200, PN0.6~PN1.6 (large-size low-pressure pipelines).
5. Copper
- Common grades: Pure Copper T2, Brass H62.
- Key properties: good thermal conductivity, freshwater corrosion resistance, hygienic and non-toxic.
- Application scenarios: air conditioning and refrigeration pipelines, domestic hot water pipelines (small-size reducers).
- Typical specifications: DN15~DN50, PN1.0~PN2.5 (low-pressure civil pipelines).
II. Non-Metallic Reducers
(Mainly for civil use, suitable for low-pressure and corrosion-resistant scenarios)
1. PVC / UPVC
- Key properties: acid and alkali resistant, lightweight, low cost, temperature resistance ≤ 60℃, low pressure resistance (PN≤1.6MPa).
- Application scenarios: civil drainage pipelines, chemical wastewater pipelines (non-high temperature).
- Connection: socket adhesive bonding; typical specifications De20~De315 (corresponding to DN15~DN300).
2. PPR
- Key properties: hygienic and non-toxic, temperature resistance ≤ 95℃, pressure resistance PN1.6~PN2.0.
- Application scenarios: domestic cold and hot water pipelines, drinking water pipelines.
- Connection: hot fusion bonding; typical specifications De20~De110 (corresponding to DN15~DN100).
3. PE (PE80 / PE100)
- Key properties: good toughness, impact resistance, buried corrosion resistance, pressure resistance PN0.6~PN1.6.
- Application scenarios: buried gas pipelines, municipal water supply networks.
- Connection: hot fusion / electrofusion bonding; typical specifications De20~De630 (corresponding to DN15~DN600).
4. FRP (Fiberglass Reinforced Plastic)
- Key properties: strong corrosion resistance (strong acid and alkali), lightweight and high strength, temperature resistance ≤ 120℃.
- Application scenarios: chemical pipelines for highly corrosive media (e.g., concentrated nitric acid, hydrochloric acid).
- Typical specifications: DN50~DN1200, PN0.6~PN2.5 (low-pressure corrosion-resistant pipelines).
III. Core Principles for Material Selection
- Medium compatibility:
- Non-corrosive media (water, oil, steam) → carbon steel;
- Corrosive media (acid, alkali, seawater) → stainless steel / FRP;
- High-temperature media (>450℃) → alloy steel;
- Hygienic requirements (food / pharmaceutical) → 304/316L stainless steel (mirror polished).
- Pressure / temperature compatibility:
- Low pressure (PN≤1.6MPa) / normal temperature → carbon steel / plastic;
- Medium and high pressure (PN2.5~PN10.0) / medium temperature → stainless steel / carbon steel;
- Ultra-high pressure (PN≥10.0) / high temperature → alloy steel.
- Scenario compatibility:
- Buried pipelines → PE / FRP (soil corrosion resistance);
- Aboveground pipelines → carbon steel / stainless steel (wind load and temperature difference resistance);
- Civil buildings → PPR / PVC (lightweight, easy installation).
