A polypropylene pump vs stainless steel pump is usually settled with a corrosion chart: run a finger down the column for the chemical, see which material says “satisfactory”, and buy that one. The chart answers a narrower question than the one being asked. It tells you whether a material survives contact with a fluid. It does not tell you what happens to the pump after two years, or whether you will find out before it fails.
Both materials are good at their job. The useful comparison is not which one resists corrosion better, because for most industrial fluids at least one of them does the job well enough. The comparison is which failure mode you can detect in time, and which one your duty conditions push you towards. This guide works through both, and closes with the four questions that override the chart.
Key takeaways
- The comparison is not which material resists corrosion better; it is which failure mode gives you a warning.
- 316L fails by chloride stress corrosion cracking, which is a brittle crack at a wall thickness that has barely changed, so ultrasonic thickness checks do not see it coming.
- Chloride SCC is rare in fully immersed 316L below 60 °C, and failures have been reported at bulk chloride levels as low as 10 ppm once evaporation concentrates them.
- PP’s boundary is not “strong acid versus weak acid”. It handles concentrated hydrochloric acid and 50% sulfuric acid at 60 °C; at that same temperature it fails on fuming sulfuric acid, concentrated nitric acid, wet chlorine, aromatics and chlorinated solvents.
- Our PP pump series is rated to 60 °C at the pump. That is a pump rating, not the resin’s limit, and the gap between the two numbers is where selection errors happen.
- The purchase-price argument for PP is weaker than it looks: upgrading the wetted end from 316L to a higher alloy is only a few percent of the installed price of the pump set.
- The weakest wetted part decides the pump’s life, and in a “PP pump” the shaft, seal faces and fasteners are still metal.
What the Comparison Is Really About
Put a polypropylene pump vs stainless steel pump question to two engineers and you will usually get two lists of chemicals. That is the wrong frame, and the corrosion literature says so fairly plainly. A technical paper on pump material selection from Weir Materials and Weir Pumps puts the priority this way: “It is much more important that the materials resist localised attack such as pitting, stress corrosion cracking and erosion corrosion as these tend to propagate rapidly and are more likely to lead to premature leakage and/or failure.” Uniform corrosion is slow, predictable and measurable; localised attack is fast, unpredictable, and often invisible until it is a leak. The two materials differ far more in how they fail locally than in whether they corrode at all.
The question is not which one resists corrosion better
For a neutral salt solution at ambient temperature, both materials can last years. 316L holds a passive chromium oxide film that repairs itself in aerated conditions; polypropylene is a non-polar hydrocarbon polymer with no ionic or hydrolysable bond for an acid to attack. On a plain compatibility chart both columns read “satisfactory” for a large share of the rows, and choosing between them on that basis is choosing on a tie. The decision only becomes interesting where the two diverge: where 316L’s passive film is attacked faster than it repairs, or where PP meets something that dissolves or swells it.
Two failure modes, two different warnings
A 316L pump usually fails in one of two ways. General corrosion thins the casing slowly enough that a thickness survey finds it. Localised attack — pitting, crevice corrosion, or chloride stress corrosion cracking — does not thin the casing first. It starts a crack and propagates it, and the wall can be almost full thickness when the pump lets go. A PP pump fails differently: it softens, swells, or creeps. The casing bulges, a flange face loses its flatness, an impeller changes shape, or a seal face distorts — visible, progressive changes you can usually see before the pump has failed.
That difference has a practical consequence for maintenance. A stainless pump needs inspection that finds cracks, not just thickness. A PP pump needs its temperature and pressure envelope respected, because the failure is a slow excursion past a limit rather than a sudden event. A plastic pump vs metal pump substitution is therefore safe only where neither material’s failure mode is in play.
| Dimension | Polypropylene (PP) | 316L stainless steel |
|---|---|---|
| Chemical resistance | Broad; limited by oxidation and by solvents, not by acidity | Depends on a passive film; limited by chlorides |
| Typical failure mode | Softening, swelling, creep — visible and progressive | Localised attack — pitting, crevice corrosion, SCC; can be invisible |
| Temperature ceiling | Set by the pump, not the resin; our series is rated to 60 °C | Far higher than a polymer |
| Pressure and head | Limited by creep and stiffness | High |
| Handling weight | Light enough for one-person handling | Needs lifting equipment |
| Position on the alloy cost ladder | Outside the ladder — it is a polymer | Mid-ladder |
Where 316L Wins, and Where It Fails Without Warning
It is worth being direct about where stainless is the better material, because a comparison that only lists its weaknesses is not a comparison. If the duty is hot, if the head is high, or if the pump must tolerate mechanical abuse and piping loads, stainless is the stronger starting point.
Strength, temperature and pressure: the stainless advantage is real
316L carries far more stress per unit of wall thickness than any polypropylene, which is why a stainless pump can be built for high heads and temperatures in a package the size of a PP pump, and why the same duty in PP needs a larger, heavier casing. It also tolerates higher nozzle loads from the connected pipework. The temperature gap is wider still: our PP series is rated for liquid up to 60 °C, while stainless has no comparable ceiling in normal chemical service. Any duty above the polymer’s envelope is a stainless duty by default, before chemistry is considered.
Chloride stress corrosion cracking
Chloride stress corrosion cracking is a brittle failure produced by three things at once: a susceptible alloy, a tensile stress, and a chloride-bearing environment. The Specialty Steel Industry of North America is blunt about the first condition: “no stainless steel grade is totally immune to chloride SCC”, and “the austenitic family of stainless steels is the most susceptible”. What exposes 316L in particular is its nickel content — “the most susceptible austenitic grades have nickel contents in the range of 8 to 10 wt%” — so that “standard grades such as 304/304L and 316/316L are very susceptible to this mode of attack”. The grade most often specified as the safe default sits, by its own composition, in the worst band.
The mechanism explains why thickness surveys miss it. Chloride ions break down the passive film at a local point and start a pit, the pit concentrates stress at its base, and a crack runs along the grain boundaries at a stress far below the alloy’s yield strength. Nothing needs to thin first. The casing can measure full wall thickness on the day it splits.
The combination that turns 316L into the wrong choice
SSINA lists four environmental factors that raise susceptibility: “higher temperatures, increased chloride content, lower pH, and higher levels of tensile stress”. A pump supplies the fourth permanently. A rotating impeller, a pressurised casing and preloaded flange bolts are all tensile stress, present for the whole service life. Three conditions are set by the process; the fourth is supplied by the equipment.
The temperature threshold is the one most often quoted, and it is worth quoting precisely: “When stainless steels are fully immersed, it is rare to see chloride stress corrosion cracking at temperatures below 60 °C.” The same threshold appears from a different direction in the Weir paper, explaining why 316 is not used for main oil line pumps: “the oil is pumped hot (e.g., 60°-70°C) and chloride stress corrosion cracking (SCC) may occur”.
Below that threshold the risk does not vanish, and two effects move it. Oxygen is the first: if dissolved oxygen falls to 0.01 to 0.1 ppm, “aqueous solutions containing low to moderate chloride levels are not likely to crack austenitic alloys, such as 304L and 316L” — against a normal oxygen solubility of 4.5 to 8 ppm at atmospheric pressure. A normally aerated pump sits far above the level at which cracking becomes unlikely. Concentration is the second: “Failures have been reported in environments with as little as 10 ppm chlorides”, and “a few ppm of chlorides in the bulk solution can concentrate to hundreds of ppm in the area of evaporation”. Under severe evaporative conditions stainless can crack “at temperatures well below the thresholds measured under conditions where there is full immersion”. Sampling the bulk liquid therefore tells you less than you think.
| Condition | What 316L does | What it means for the pump |
|---|---|---|
| Fully immersed, below 60 °C, low chloride, deaerated | SCC is rare | 316L is a reasonable default |
| Fully immersed, below 60 °C, chloride present, aerated | Pitting appears first; SCC possible at high stress | Inspect for pitting, not only for wall loss |
| Above 60 °C with chloride present | SCC becomes the governing risk | Move to a grade with better chloride resistance, or to a polymer |
| Any temperature with evaporation or wet-dry cycling | Chloride concentrates; failures reported from 10 ppm bulk | Bulk chloride analysis understates the risk |
| Dissolved oxygen below 0.01–0.1 ppm | Low-to-moderate chloride unlikely to crack 304L/316L | Deaeration changes the answer |
Where PP Wins, and What It Cannot Do
The most repeated statement about polypropylene pumps is that they are for weak acids and mild service. It is wrong, and a resin producer’s own compatibility data shows why.
The chemistry PP actually handles
INEOS publishes a PP chemical resistance guide that rates each reagent as satisfactory, some attack, or unsatisfactory at 21 °C, 60 °C and 100 °C. The 60 °C column is the one that matters here, because it is the top of our pump’s rated envelope. In that column, polypropylene is rated satisfactory for hydrochloric acid at 20% and at 100% concentration, hydrobromic acid at 50%, sulfuric acid at 10% and at 50%, phosphoric acid at 85%, concentrated caustic soda, potassium hydroxide, ferric chloride, and glacial acetic acid.
That is not a mild-service list. It is most of what a chemical plant pumps. The reason is structural: polypropylene is a saturated hydrocarbon polymer. It has no ester, amide or carbonate bond for an acid to hydrolyse and no ionic species to exchange. Acidity is largely irrelevant to it. What attacks polypropylene is oxidation, and what dissolves or swells it is a solvent that shares its non-polar character.
Hydrofluoric acid is the one acid where the 60 °C rating changes: the guide rates 35% HF satisfactory at 21 °C but only some attack at 60 °C. Where HF is involved, the temperature at the pump is the deciding number, not the concentration.
What PP genuinely cannot take
The same table marks the real boundary, and it is nowhere near where the folklore puts it. Polypropylene is rated unsatisfactory for fuming sulfuric acid and oleum, for fuming nitric acid, and for a 50/50 nitric-sulfuric mixture. Concentrated nitric acid is rated some attack at 21 °C and unsatisfactory at 60 °C. Wet chlorine is some attack at 21 °C and unsatisfactory at 60 °C; dry chlorine is unsatisfactory at both. Concentrated sodium hypochlorite is satisfactory at 21 °C, some attack at 60 °C, and unsatisfactory at 100 °C.
The solvent side is less intuitive. Toluene, perchloroethylene, trichloroethylene, carbon tetrachloride, styrene and white spirits are all rated unsatisfactory at both 21 °C and 60 °C. Xylene, chloroform and benzene are some attack at 21 °C and unsatisfactory at 60 °C. Heptane is unsatisfactory across all three temperatures. A polypropylene pump is a poor choice for a chlorinated solvent transfer duty even though it is an excellent choice for hydrochloric acid.
There are also results that resist reasoning. Chromic acid at 10% and at 50% is rated satisfactory at both 21 °C and 60 °C in the same table, even though it is a strong oxidiser. That is the argument for reading the chart rather than predicting from a chemical’s reputation — in either direction.
Where the duty is chemical transfer inside these limits, the PP wet end is the point of the exercise; the PP centrifugal pump range is built around it.
Why two charts disagree
Take one row and compare two published guides. For 10% nitric acid, the INEOS table rates polypropylene satisfactory at 21 °C, 60 °C and 100 °C. A polypropylene chemical resistance guide published by IPEX caps 10% nitric acid at 40 °C. Both are manufacturer data. Neither states the test method, the exposure time, or whether the rating reflects mass change, dimensional change or residual strength.
The INEOS guide carries its own warning: the information “concerns general chemical resistance only”, and because “other factors such as permeation, ESCR and container design are involved, full compatibility testing is recommended”. That is the correct way to read any compatibility table. It is a screening tool that removes clearly unsuitable candidates. It is not an approval, and where two tables disagree the only resolution is a test or a written statement from the pump supplier for that fluid, at that concentration, at that temperature.
The Temperature Ceiling Is the Pump’s, Not the Resin’s
Three different temperature numbers circulate for polypropylene, and mixing them up is the most common way a PP pump gets specified for a duty it cannot hold.
Three numbers that are not the same number
The first is the resin’s continuous service temperature, a materials figure that describes when the polymer itself begins to soften or degrade. The second is the design stress a piping standard allows at a given temperature and design life; ISO 3213:1996, Polypropylene (PP) pipes — Effect of time and temperature on the expected strength, is built entirely around the fact that this number is a function of both. Its reference lines cover 20 °C to 95 °C. The third is the pump rating, and for our series that is 60 °C.
The three numbers are not interchangeable, and the pump number is the lowest of them. That is not conservatism for its own sake. It is a different load case.
Why the pump number is lower
A pipe wall carries hoop stress in a shape that stays put. A pump casing carries pressure while holding a rotating cantilever impeller, a mechanical seal with preloaded faces, and bolted flanges whose joint integrity depends on bolt preload being maintained. Every one of those is a sustained load on a polymer that creeps — that is, deforms progressively under constant stress. ISO 3213’s title says exactly this: the expected strength depends on time as well as temperature.
The seal is usually the binding constraint before the casing is. The elastomer and the face materials have their own temperature and chemical limits, and they are not the same as the resin’s. A PP casing that is comfortable at a given temperature can still be carrying a seal that is not. Which elastomer and which face grade survive a given medium is a separate question, worked through in mechanical seal for chemical duty.
So 60 °C is where our series is rated, and the honest answer above that is a different wet end — PVDF, whose piping counterpart ISO 10931 is named in ISO 15494, or a lined metal pump. Making the PP wall thicker does not move the ceiling, because the limit is not wall stress; it is the time-dependent behaviour of the material and the temperature limits of the parts inside it.
If the duty is within the envelope, the rest of the selection — flow, head, specific gravity, NPSH — follows the method in our polypropylene pump selection guide. Temperature is the input that most often removes PP from the list before any of that arithmetic starts.
| Temperature band | What the standards describe | What it means for a PP pump |
|---|---|---|
| Below 20 °C | Below the lower end of the ISO 3213 reference range | Outside what the reference lines describe; confirm with the supplier |
| 20–60 °C | Inside the ISO 3213 range and inside our series rating | Normal PP duty |
| 60–95 °C | Inside the ISO 3213 range, above our pump rating | PP pipe may be rated here; our PP pump is not |
| Above 95 °C | Outside the ISO 3213 range entirely | Move to PVDF or a lined metal pump |
What the Four Materials Actually Cost
Material cost is the argument people expect to settle chemical pump material selection, and it is the weakest of the arguments once the numbers are looked at properly.
The ladder, and where PP sits on it
The Weir paper publishes the ladder reproduced below, with a caveat worth carrying: the order is “roughly the order of corrosion resistance in seawater, although the corrosion ranking order can change dramatically in other fluids.”
Polypropylene is not on that ladder, because it is not an alloy. It sits outside the sequence rather than at the bottom of it, so a PP-versus-stainless cost comparison is not a like-for-like substitution: the stainless pump is buying strength and temperature headroom that a PP pump does not have.
Where the crossover actually sits
The more useful cost finding in the Weir paper is about how little a wetted-end upgrade costs relative to the whole machine. Taking a complex injection pump set as the example, the authors report that “an upgrade from 316 stainless steel to super duplex stainless steel increases the total cost of the wetted components by ~15%. However, the cost of the rest of the components on the skid is fixed and the upgrade represents an increase of ~2% of the total price.”
Read that against the common assumption that a premium material is unaffordable. The wetted end can move a full alloy step for a few percent of installed cost, because motor, baseplate, coupling, instrumentation and the rest of the skid do not change. Which means the purchase price is rarely the deciding term. What decides it is whether the cheaper material fails early.
The same paper gives the counter-example that keeps this honest. A pump for quarry water that was acidic with a high chloride content would normally need 316 stainless at minimum, possibly duplex. The specification required the pump to last three months. For that life, cast iron was the most cost-effective answer. Cost is a function of required life, not a property of the material.
For a scrubber recirculation duty, where the chemistry is aggressive and the loop is closed, the same reasoning runs through the PP pump for wet scrubber sizing method.
| Position, increasing cost | Material | What the extra cost buys |
|---|---|---|
| Lowest | Cast iron, carbon steel | Neutral fluids and short required life |
| ↓ | Martensitic stainless, austenitic cast iron, gunmetals, nickel aluminium bronze | Seawater and mild corrosive service |
| ↓ | 316 stainless steel | General chemical service without chloride at temperature |
| ↓ | Duplex and super duplex stainless steel | Chloride resistance and higher strength |
| ↓ | Nickel alloys | Oxidising acids, chlorides, mixed acid service |
| Highest | Titanium | The most aggressive chloride duties |
| Outside the ladder | Polypropylene | Chemistry, within a pump rated to 60 °C |
The Wetted Parts Nobody Checks
A corrosion resistant pump is only as resistant as its least resistant wetted part, and material selection usually stops at the casing and assumes the rest. The Weir paper opens its section on corrosion with the opposite instruction: “It is important to consider all the components in the pump and not just the major ones.”
The parts that instruction refers to are listed by material and by wear order in centrifugal pump parts.
A stainless casing with the wrong fasteners is not a stainless pump
The paper’s first example is worth repeating in full, because it is the failure nobody predicts. A submersible seawater pump was built in super duplex stainless steel, and the contractor connecting the motor and pump on the platform used 316 stainless bolts. Several years later, when the column and pump were lifted for maintenance, the motor and pump separated. The 316 bolts had suffered severe crevice corrosion and fractured during the lifting operation.
The casing was correctly specified. The pump still failed, because the fastener was a different alloy with different chloride behaviour and a galvanic relationship to the surrounding material. The paper’s second example is the same problem from the other direction: graphite-loaded seals and bearings, chosen without noting the graphite content, cause localised corrosion of most metals in contact with them in water.
What a “PP pump” still has in metal
The same logic applies to a polypropylene pump, and it is where buyers are most often surprised. A PP wet end means the casing, impeller and cover are solid polypropylene. It does not mean the pump is entirely polymer. The shaft or shaft sleeve is metal, the mechanical seal has metal or ceramic faces and elastomeric secondary sealing elements, the wear rings may be metal or filled polymer, and the fasteners are metal.
Every one of those is a wetted part, and the pump’s chemical life is set by the weakest of them. A PP pump handling hydrochloric acid has a casing that does not care about the acid and a shaft that may. That is not a reason to avoid PP; it is a reason to specify the whole wetted-parts list rather than the headline material. The polypropylene chemical pump page lists what is solid PP and what is not.
The interaction is not confined to the pump. The Weir paper warns that “other items in the system, such as pipes, flanges, etc. must be compatible”; a correctly specified pump bolted to an incompatible flange is still a corrosion cell.
| Wetted part | What it is in a PP pump | What decides it |
|---|---|---|
| Casing, impeller, cover | Solid polypropylene | The chemical resistance table |
| Shaft or shaft sleeve | Metal | The same table, plus chloride SCC risk |
| Wear rings | Metal or filled polymer | Erosion and running clearance |
| Seal faces | Silicon carbide, carbon or PTFE | Abrasion and chemistry |
| Seal elastomers | EPDM, FKM or PTFE | Chemistry at the operating temperature |
| Fasteners | Stainless steel | Crevice corrosion and galvanic pairing |
Run the Decision in Ten Minutes
Seven questions, asked in this order, will resolve most polypropylene pump vs stainless steel decisions before anyone opens a compatibility chart. The order matters: the first two can remove a material before chemistry is considered at all.
Seven questions
First, what is the fluid, exactly — not its family, but its concentration at the pump, including during cleaning and process upsets. Second, what is the temperature at the pump, not in the tank. Third, is there chloride in the fluid, and is there any surface where it can evaporate or dry? Fourth, is the fluid aerated or deaerated? Fifth, what flow and head does the duty need? Sixth, is the fluid aromatic, chlorinated, or a strong oxidiser? Seventh, how long must the pump last, and what does a failure cost in downtime?
Questions one to four decide chemistry and material. Questions five and six decide whether the mechanical envelope is available. Question seven decides whether the answer is worth paying for.
Reading the answers
If the temperature at the pump is above 60 °C, PP is outside its rating regardless of how well it handles the fluid, and the conversation moves to PVDF or a lined metal pump. If there is chloride and the temperature is above 60 °C, 316L is carrying SCC risk as well, and the answer is duplex, super duplex or a polymer. If there is chloride and any evaporating surface, bulk chloride analysis is not a safe basis for the decision at any temperature.
If the fluid is aromatic, chlorinated, or a strong oxidiser, PP is out per the resistance table and the answer is a metal. If the head is high or the duty is mechanically demanding, stainless is the stronger starting point. If none of those conditions applies — aggressive chemistry, moderate head, 60 °C or below — PP is doing exactly the job it was made for, and the lighter wet end is a maintenance advantage as well as a materials one.
The type of centrifugal pump that wet end is built into is a separate decision from the material, and it is covered in types of centrifugal pump.
For water-side duties at the low end of that range, the PP water pump range covers the same construction without the chemical-service specification.
| Question | If yes | If no |
|---|---|---|
| Is the temperature at the pump above 60 °C? | PP is outside its rating; move to PVDF or a lined metal pump | Continue |
| Is there chloride with temperature, or an evaporating surface? | 316L carries SCC risk; consider duplex or a polymer | Continue |
| Is the fluid aromatic, chlorinated, or a strong oxidiser? | PP is unsuitable per the resistance table | Continue |
| Is the head high, or the duty mechanically demanding? | Stainless is the stronger starting point | PP can carry the duty |
Frequently Asked Questions
Is polypropylene as chemical resistant as stainless steel?
For many industrial fluids, yes, and for some it is better. Polypropylene is rated satisfactory at 60 °C for hydrochloric acid at 20% and at 100%, sulfuric acid at 50%, concentrated caustic soda and glacial acetic acid. It cannot resist strong oxidisers, halogens, or aromatic and chlorinated solvents. Stainless resists many of those but is limited by chloride stress corrosion cracking at temperature. The two materials cover different halves of the chemical map.
At what temperature does chloride stress corrosion cracking start in 316 stainless steel?
Fully immersed stainless is rarely affected below 60 °C, according to SSINA, and four factors raise susceptibility: temperature, chloride content, lower pH and tensile stress. Below 60 °C the risk does not disappear. Failures have been reported from bulk chloride as low as 10 ppm where evaporation concentrated it, and cracks can occur well below the immersion threshold at a wet-dry interface.
Can a polypropylene pump handle hydrochloric acid?
The material can. INEOS rates polypropylene satisfactory for 20% and for 100% hydrochloric acid at 21 °C and 60 °C, and only some attack at 100 °C. Whether a particular pump can is a separate question, because the shaft, seal faces, seal elastomers and fasteners are not polypropylene. Check the whole wetted-parts list against the acid and confirm the seal materials with the supplier.
Why is a PP pump rated to 60 °C when PP resin handles more?
Because the resin figure and the pump rating describe different load cases. A pump adds a rotating cantilever impeller, a seal with preloaded faces, bolted flanges that depend on maintained preload, and a casing under sustained pressure — all sustained loads on a polymer that creeps with time and temperature. ISO 3213 is built on the same principle for PP pipe: expected strength depends on time and temperature together.
Is PP or PVDF the better choice for hot acid?
PVDF, when the temperature at the pump exceeds the PP rating. It is a fluoropolymer with a higher service temperature and broader resistance to strong oxidisers, and it is the standard step up when the PP envelope is exceeded. ISO 15494 names ISO 10931 as the PVDF piping counterpart, as ISO 3213 covers PP. The cost difference is real, so confirm the duty genuinely exceeds the PP envelope.
When should I choose stainless steel over polypropylene?
When the temperature at the pump exceeds the PP rating, when the head or the mechanical duty is high, or when the fluid is aromatic, chlorinated or a strong oxidiser. Also when the fluid carries chloride at temperature but the mechanical duty rules out a polymer — then the answer is duplex or super duplex, because 316L sits in the most SCC-susceptible nickel band.
Sources
- Specialty Steel Industry of North America. Chloride Stress Corrosion Cracking. Alloy composition, environmental factors, the 60 °C immersion threshold, dissolved oxygen, the 10 ppm failure report, and the boiling salt solution comparison table. ssina.com
- INEOS Olefins & Polymers USA. PP Chemical Resistance Guide, February 2012. Ratings at 21 °C, 60 °C and 100 °C for the reagents cited, and the guide’s own limitation to general chemical resistance. ineos.com
- IPEX. Polypropylene Chemical Resistance Guide. Concentration-specific maximum service temperatures for hydrochloric, hydrofluoric, sulfuric and nitric acid and for sodium hydroxide. ipexna.com
- R. Francis, Weir Materials & Foundries, and L. Phillips, Weir Pumps Ltd. Cost effective materials selection for pumps. Localised attack priority, the 60–70 °C SCC note for 316, the material cost ladder, the wetted-component upgrade arithmetic, the 316 fastener failure case, and the graphite seal warning. neonickel.com
- International Organization for Standardization. ISO 3213:1996, Polypropylene (PP) pipes — Effect of time and temperature on the expected strength. Scope and clause 4, covering the 20 °C to 95 °C reference lines. iso.org/standard/22752.html
- International Organization for Standardization. ISO 15494:2015, Plastics piping systems for industrial applications — PB, PE, PE-RT, PE-X, PP. Introduction, naming ISO 10931 as the PVDF counterpart. iso.org/standard/55627.html
