Material Selection for Thermoplastic Piping

A Deep Dive into the STAMP Approach

Selecting the right piping material isn’t just about what fits—it’s about what lasts. In industrial applications, improper material selection can result in premature failures, unplanned shutdowns, safety hazards, and costly repairs.

One proven engineering approach to material selection is the STAMP method—a structured way to ensure your thermoplastic piping system matches the demands of your application, especially when dealing with aggressive chemicals.

In this guide, we’ll explain the STAMP acronym and show you how to apply it when selecting thermoplastic piping materials for industrial chemical handling.

STAMP method of material selection in thermoplastics

What Is STAMP?

STAMP stands for:

• S: Size

• T: Temperature

• A: Application

• M: Media (chemical compatibility)

• P: Pressure

It’s a widely used technique in engineering for material specification, particularly in the selection of piping, valves, and fittings in complex environments.

🧪 M — MEDIA (Chemical Compatibility)

This is the most critical step when dealing with aggressive environments like acids, alkalis, solvents, and oxidizers. Choosing the wrong material for your chemical can lead to swelling, brittleness, cracking, or catastrophic failure.

Key Questions:

• What chemical or chemical mixture is being conveyed?

• What is its concentration?

• Is the media oxidizing, reducing, organic, or inorganic?

• Is there abrasion potential, or slurries involved?

• Are there cleanliness or purity requirements?

Selecting Thermoplastics Based on Media:

Thermoplastic	Best For	Avoid With
PP / PPH	Diluted acids, bases, salts	Strong oxidizing agents
PVDF	HF, strong acids, high-purity media	Long exposure to hot caustic solutions
CPVC	General industrial acids and alkalis	Aromatic and chlorinated solvents
ECTFE	Chlorine, bleach, mixed chemical resistance	High cost may be a limiting factor
PFA	Universal chemical resistance	High upfront cost
PE 100	Water, saltwater, mild acids	Solvents, hydrocarbons
PPS	Fuels, organic solvents	Strong mineral acids

Always consult a chemical resistance chart or get a third-party validation if handling a novel or mixed chemical process.

🌡 T — TEMPERATURE

Every thermoplastic has a maximum operating temperature, above which it softens, deforms, or degrades chemically. Chemical resistance often decreases at higher temperatures.

Material	Max Continuous Temp.
PP / PPH	~90–100°C
CPVC	~93°C
PVDF	~140°C
ECTFE	~150°C
PFA	~260°C

Important: A material that resists a chemical at room temperature may fail under heat. Always cross-check chemical resistance at the actual process temperature.

⚙️ A — APPLICATION

Understanding the function and environment is vital.

Ask:

• Is this pressure piping, drainage, or ventilation?

• Will there be exposure to UV, abrasion, or mechanical stress?

• Does the application require ultrapure, conductive, or anti-static piping?

Examples:

• Semiconductor ultrapure water → PVDF or PFA (high purity, clean welds)

• Waste acid drain line → PP, CPVC, or PE based on temperature

• Electroplating tanks → PP with fiberglass reinforcement

🧩 S — SIZE

While this seems simple, it's not just about nominal diameter.

Consider:

• Is this a batch or continuous process?

• What are the flow rates and pipe lengths?

• Will thermal expansion affect long runs?

Thermoplastics expand more than metals. For example, PVDF and PP may require expansion loops or anchors in above-ground installations.

⚠️ P — PRESSURE

Thermoplastic pressure ratings are usually given at 20°C, and derated at higher temperatures. For high-pressure systems, always refer to ISO 4427, DIN 8077/8078, or manufacturer data.

Material	Pressure Rating (PN)	Derating At 60°C
PE 100 PN16	16 bar @ 20°C	~10 bar @ 60°C
PVDF PN10	10 bar @ 20°C	~6.3 bar @ 60°C

If you’re dealing with pulsating flow, vacuum, or compressible gases, consider reinforced systems or pressure-rated fittings.