Phosphates & Corrosion Inhibitors
Sodium Tripolyphosphate (STPP)
CAS 7758-29-4 — Detergent Builder & Sequestrant
STPP is the primary builder in heavy-duty detergents and a key sequestrant in water treatment, food processing, and ceramic manufacturing. Texas-Chem supplies industrial and food-grade STPP in bulk drums, totes, and super sacks.
CAS Number
7758-29-4
Formula
Na₅P₃O₁₀
pH (1% solution)
9.5–10.0
Pack Sizes
Bags · Super Sacks · Bulk
Structure / Diagram
Na₅P₃O₁₀ — Sodium Tripolyphosphate — CAS 7758-29-4
Safety & Regulatory
- NFPA Health
- 2 — Moderate irritant
- NFPA Flammability
- 0 — Non-flammable
- NFPA Reactivity
- 0 — Stable
- OSHA PEL (dust)
- 5 mg/m³
- DOT Hazard Class
- Not regulated
- Skin/Eye
- Irritant — wear gloves and safety glasses
Grades & Packaging
Available Grades
Pack Sizes
Also Known As
Physical & Chemical Properties
| CAS Number | 7758-29-4 |
| Molecular Formula | Na₅P₃O₁₀ |
| Molecular Weight | 367.86 g/mol |
| Appearance | White granular or powder |
| Solubility in Water | 14.5 g/100 mL at 25 °C |
| pH (1% solution) | 9.5–10.0 |
| Melting Point | 622 °C (decomposes) |
| Bulk Density | 0.7–1.0 g/cm³ (granular) |
| Phosphorus Content | ~25.3% as P₂O₅ |
| Hygroscopicity | Moderate — store in sealed containers |
| Sequestration (Ca hardness) | Excellent — 12–15 mg CaCO₃/g |
| Grades Available | Industrial / Food Grade (FCC) |
Industrial Applications
Detergent Manufacturing
STPP is the primary builder in heavy-duty laundry and automatic dishwasher detergents, sequestering calcium and magnesium ions to prevent scale and boost surfactant performance in hard water.
Water Treatment
Used as a scale and corrosion inhibitor in cooling water systems and boiler feedwater treatment, sequestering hardness ions that cause scale deposits on heat transfer surfaces.
Food Processing
Food-grade STPP is used as a moisture retention agent in seafood, poultry, and meat processing, and as an emulsifier and texturizer in processed cheese and canned foods (E451).
Ceramic & Tile Manufacturing
STPP is used as a deflocculant in ceramic slurries, reducing viscosity and improving workability of clay bodies for tile, sanitaryware, and technical ceramic production.
Industrial Cleaning
Used as a builder and sequestrant in industrial and institutional cleaning formulations, boosting surfactant performance and preventing scale in hard water cleaning applications.
Paper & Pulp
STPP is used as a dispersant and sequestrant in paper manufacturing, preventing scale in process water systems and improving pigment dispersion in paper coatings.
Why Source STPP from Texas-Chem
- Industrial and food-grade STPP in stock — drums, totes, and super sacks
- Consistent quality with CoA on every lot
- Same-week delivery across Texas; nationwide LTL
- Technical support for detergent, water treatment, and food applications
- One rep from first call to final delivery
STPP — Frequently Asked Questions
What is the difference between STPP and SHMP for water treatment?▾
STPP (sodium tripolyphosphate) is a linear polyphosphate with excellent calcium and magnesium sequestration at pH 9.5–10.0. SHMP (sodium hexametaphosphate) is a cyclic polyphosphate with broader sequestration including iron, and operates at near-neutral pH (6.5–7.5). STPP is preferred for alkaline detergent and boiler water applications; SHMP is preferred for municipal water treatment and oilfield applications. Contact Texas-Chem at 855-TEX-CHEM for application guidance.
Is food-grade STPP available?▾
Yes. Texas-Chem supplies food-grade STPP meeting FCC (Food Chemicals Codex) specifications for use in seafood processing, meat processing, and processed cheese manufacturing. Food-grade STPP is listed as GRAS (Generally Recognized as Safe) by the FDA and approved as food additive E451 in the EU. Contact us for food-grade CoA and specification sheets.
What is the typical treat rate for STPP in laundry detergent?▾
STPP is typically used at 15–30% by weight in heavy-duty powder laundry detergents and 5–15% in liquid detergents. The treat rate depends on the water hardness in the target market and the desired cleaning performance. Higher treat rates are used in hard water markets (Texas, Southwest US) where calcium and magnesium concentrations are high.
How should STPP be stored?▾
STPP is moderately hygroscopic and should be stored in sealed containers or bags in a dry location. Exposure to moisture causes hydration and caking. Granular STPP is less hygroscopic than powder grades. Store away from acids and oxidizing agents. Shelf life is 2 years in sealed original packaging.