One-Stop Supply of PP, PPH & HDPE Sheets, Pipes & Welding Rods
Views: 0 Author: Site Editor Publish Time: 2026-08-19 Origin: Site
Selecting the right PPH sheet thickness for a chemical storage tank is not as simple as choosing 10 mm, 15 mm, or 20 mm according to tank capacity.
Two tanks with exactly the same volume can require very different wall thicknesses.
Why?
Because the required thickness depends on the chemical being stored, specific gravity, liquid height, tank diameter, operating temperature, tank geometry, design life, reinforcement system, welding efficiency, nozzles, and external loads.
For fabricated thermoplastic tanks, engineering standards such as DVS 2205 use these operating conditions to determine the allowable material stress and structural requirements rather than selecting wall thickness from tank volume alone.
This guide explains how PPH tank wall thickness is selected and what information you should provide to a PPH sheet supplier or tank fabricator before ordering material.
There is no universal PPH sheet thickness for a given tank capacity.
A proper thickness recommendation normally requires at least:
Design Parameter | Why It Matters |
|---|---|
Chemical | Determines material compatibility |
Concentration | Can significantly change chemical resistance |
Specific gravity | Determines the weight of liquid acting on the tank wall |
Operating temperature | Affects the long-term mechanical strength of PPH |
Tank height | Determines maximum hydrostatic pressure |
Tank diameter or width | Influences structural wall stress |
Tank shape | Cylindrical and rectangular tanks behave differently |
Design life | Thermoplastics must be evaluated for long-term creep |
Reinforcement | Can significantly change wall requirements |
Nozzles and equipment | Can create additional local stresses |
Indoor/outdoor installation | May introduce UV, wind, snow or seismic loads |
Design standard | Determines the engineering calculation method |
Petron Thermoplast, for example, specifies PPH tank wall thickness as something that must be calculated from capacity, specific gravity and operating conditions rather than providing one universal wall thickness.
So if a supplier recommends a PPH sheet thickness after knowing only the tank volume, ask for the engineering basis behind that recommendation.
Consider two 10 m³ cylindrical tanks.
Tank A is relatively short and wide.
Tank B is tall and narrow.
Although both tanks hold the same volume, the liquid pressure near the bottom of Tank B may be very different because hydrostatic pressure depends heavily on liquid height.
At the same time, tank diameter affects circumferential or hoop stress.
This means:
Tank volume tells you how much liquid is stored. It does not tell you the stress distribution in the tank wall.
The same problem occurs when comparing chemicals.
A tank containing a liquid with a specific gravity of 1.05 does not impose the same structural load as a tank of identical dimensions containing a liquid with a specific gravity of 1.80.
Temperature adds another layer.
PP-H is valued in chemical tank construction partly because of its chemical resistance, weldability, stiffness and useful properties at elevated temperatures. However, plastic design must consider long-term material behaviour rather than relying only on room-temperature tensile strength.
That is why a simple chart such as:
“1,000 L = 10 mm”
or
“10,000 L = 20 mm”
should never be treated as a final engineering specification.
The first question should not be:
How large is the tank?
It should be:
What chemical will the tank contain?
PPH offers strong resistance to many acids, alkalis, salts and industrial chemicals, which is one reason it is commonly used for chemical processing and tank fabrication. However, chemical compatibility must always be evaluated against the exact chemical, concentration and temperature involved.
Chemical resistance and structural strength are also different questions.
A material may show good chemical compatibility with a liquid while still requiring additional wall thickness because of temperature, long-term loading or high specific gravity.
Never specify a chemical tank using only a statement such as:
“Tank for acid.”
Instead specify something like:
Sulfuric acid, 30 wt%, normal operating temperature 50°C, maximum design temperature 65°C.
The more precise the chemical specification, the more reliable the material and thickness selection.
Specific gravity, often abbreviated as SG, is one of the most important parameters when determining PPH tank wall thickness.
Water has an SG of approximately 1.0.
Many industrial chemicals are heavier.
As specific gravity increases, the mass of liquid contained in the tank increases, which increases the load acting on the tank structure.
For this reason, specifying only tank capacity is insufficient.
For example, a 5,000-liter tank containing water and a 5,000-liter tank containing a high-density chemical do not create the same structural loading.
Poly Processing similarly identifies chemical specific gravity as a major factor in chemical tank wall design, alongside temperature and tank geometry.
For an accurate quotation, always provide either:
Specific gravity at operating temperature
or enough chemical information for the designer to determine it.
Hydrostatic pressure increases with liquid depth.
The basic relationship is:
p = ρgh
where:
p = hydrostatic pressure
ρ = liquid density
g = gravitational acceleration
h = liquid height
This explains why the lower section of a tall chemical tank experiences substantially more liquid pressure than the upper section.
For cylindrical tanks, diameter is also important because hydrostatic pressure acting over a larger cylinder affects circumferential wall stress.
A simplified thin-wall relationship often used to understand the principle is:
Hoop stress ∝ pressure × diameter / wall thickness
This is only a conceptual relationship.
A real PPH tank calculation must also account for allowable long-term material stress, temperature, chemical exposure, welded joints, safety factors, design life and other loads. DVS 2205 calculations for cylindrical thermoplastic tanks explicitly consider hydrostatic head, design pressure, allowable stress and safety factors.
The practical lesson is simple:
Always provide tank diameter and liquid height—not just tank volume.
Temperature can dramatically affect thermoplastic tank design.
PPH is attractive for many chemical-processing applications because PP-H combines chemical resistance with relatively high rigidity at elevated service temperatures compared with PE. SIMONA, for example, positions PP-H specifically for chemical tank and equipment construction and highlights its long-term properties and high rigidity in the upper temperature range.
However, the temperature resistance of the material does not mean the same wall thickness can be used at every temperature.
As temperature rises, the allowable long-term mechanical stress used in the structural calculation may decrease.
Consequently:
A PPH tank operating at 70°C may require a different structural design from an identical tank operating at 20°C.
For this reason, specify both:
Normal operating temperature
and
Maximum design temperature.
Do not simply provide the highest theoretical material temperature rating.
The designer needs the actual operating conditions.
This is one of the biggest differences between designing a plastic tank and making a simple plastic box.
Chemical storage tanks may remain filled continuously for years.
Thermoplastics under sustained load exhibit creep, meaning their deformation and mechanical behaviour change over time.
Therefore, tank design should be based on long-term material performance rather than only short-term tensile strength.
DVS 2205 incorporates long-term material behaviour and reduction factors when deriving allowable design stresses for thermoplastic equipment.
This is why the intended service life matters.
A tank designed for occasional temporary use and a chemical storage tank expected to operate continuously for 20 years should not automatically receive the same design.
When requesting a tank calculation, state the required design life whenever possible.
Tank geometry fundamentally changes how the walls are loaded.
Round tanks handle internal hydrostatic loading efficiently because the load is distributed around the circumference.
For large vertical cylindrical tanks, different shell sections may use different PPH sheet thicknesses.
Flat walls are much more susceptible to bending and deformation.
Therefore, rectangular PPH tanks often require:
external stiffeners,
PP reinforcement ribs,
structural steel frames,
tie rods,
shorter unsupported panel spans,
or thicker sheet.
DVS 2205 treats vertical cylindrical tanks and rectangular tanks separately, while Röchling's RITA engineering software likewise calculates cylindrical tanks and rectangular tanks using different structural models and can optimise reinforcement for rectangular tanks.
This means you cannot take a wall thickness calculated for a cylindrical tank and automatically apply it to a rectangular tank of the same volume.
Real chemical tanks are rarely just empty cylinders with liquid inside.
They may contain:
inlet and outlet nozzles,
drain connections,
manholes,
level instruments,
overflow pipes,
mixers or agitators,
heating coils,
ladders,
platforms,
lifting points,
external piping.
Every penetration or attached component can affect the stress distribution.
Large nozzles, for example, remove material from the tank shell and can create stress concentrations around the opening.
An agitator can introduce mechanical loads that are completely different from static hydrostatic pressure.
Outdoor tanks may additionally need to consider:
wind,
snow,
seismic loading,
solar exposure,
anchoring.
Modern thermoplastic tank design tools such as Röchling RITA explicitly include nozzle positioning and can account for wind, snow and earthquake loads in applicable tank designs.
Therefore, accessories should be defined before final wall thickness is approved, not added as an afterthought.
The exact calculation depends on tank geometry and the applicable engineering standard, but the general process looks like this.
The designer establishes:
chemical,
concentration,
specific gravity,
minimum and maximum temperature,
tank dimensions,
maximum filling level,
pressure or vacuum conditions,
service life,
installation environment,
and operating cycles.
Before calculating thickness, the material itself must be confirmed as suitable for the medium.
Increasing wall thickness cannot compensate for fundamentally incorrect chemical compatibility.
If PPH is not suitable for the chemical and temperature combination, another material such as HDPE, PVC, CPVC, PVDF or a composite construction may need to be considered.
For an atmospheric chemical storage tank, hydrostatic loading is usually one of the principal loads.
Maximum hydrostatic pressure occurs near the bottom of the liquid column.
The calculation must then consider additional loads when applicable, including tank self-weight, roof loads, external piping loads, wind, seismic forces and equipment loads.
This is where a proper thermoplastic calculation becomes much more sophisticated than simply dividing short-term tensile strength by a safety factor.
The designer may have to consider:
long-term material properties,
design temperature,
chemical exposure,
weld factors,
safety factors,
service life.
DVS 2205 provides a structural design framework for thermoplastic tanks and equipment, while its different sections address cylindrical tanks, welded joints, flange joints and rectangular tanks.
For cylindrical tanks, hydrostatic pressure and circumferential stress become key design considerations.
For rectangular tanks, wall bending, unsupported span and reinforcement spacing often become more important.
The calculated value is then converted into a practical available sheet thickness while satisfying applicable minimum construction and fabrication requirements.
Wall thickness is only one part of tank integrity.
A complete design should also consider:
tank bottom,
roof,
welded seams,
flanges,
nozzles,
reinforcement,
anchoring,
lifting arrangements,
supports.
A 20 mm wall does not make a tank safe if a nozzle connection or weld detail is badly designed.
Not necessarily.
Large cylindrical PPH tanks can be manufactured using different sheet thicknesses at different heights.
The reason is hydrostatic pressure.
Pressure is greatest near the bottom and progressively decreases toward the top.
Consequently, the lower shell section may require thicker material than the upper shell.
A simplified concept might look like:
Upper shell → thinner PPH sheet
Middle shell → intermediate thickness
Lower shell → thicker PPH sheet
This approach can optimise material use while maintaining structural performance.
It also explains why asking:
“What thickness does a 20 m³ PPH tank need?”
does not have one universal answer.
A documented AGRU project provides a useful real-world example.
Three PP-H tanks were manufactured for sulfuric acid service with approximately the following conditions:
Parameter | Specification |
|---|---|
Material | |
Geometric volume | 20 m³ |
Working volume | 18 m³ |
Internal diameter | 2,200 mm |
Height | 5,220 mm |
Chemical | 10–40% sulfuric acid |
Operating temperature | Up to 70°C |
Pressure | Atmospheric |
Design life | 20 years |
Wall thickness | 15–45 mm |
Design basis | DVS 2205 |
The wall thickness varies dramatically within one tank—from 15 mm to 45 mm.
This example demonstrates an important engineering principle:
PPH sheet thickness should follow the load at each part of the tank rather than being selected from capacity alone.
It also explains why buying all tank sheets in one thickness can sometimes increase material cost unnecessarily.
Two references commonly encountered in welded thermoplastic tank engineering are DVS 2205 and EN 12573.
DVS 2205 provides detailed calculation guidance for thermoplastic tanks and equipment.
For example:
DVS 2205-2 addresses vertical round non-pressurised thermoplastic tanks, while other parts of the DVS 2205 family cover basic material/design principles, welded joints, flanges and rectangular tanks.
The EN 12573 series covers welded static non-pressurised thermoplastic tanks, with separate parts covering areas including vertical cylindrical and rectangular tanks. BSI currently lists the relevant EN 12573 parts as current and under review.
Which standard should be used depends on:
project location,
customer specification,
engineering requirements,
regulatory requirements,
tank geometry,
fabricator capability.
For international industrial projects, the design standard should ideally be agreed before fabrication begins.
For a vertical cylindrical tank, the circular structure naturally distributes internal liquid pressure around the circumference.
Important inputs include:
liquid height,
diameter,
SG,
temperature,
design life,
pressure,
shell openings.
Cylindrical tanks can also use stepped wall thicknesses, particularly for larger structures.
A rectangular tank behaves differently.
Large flat panels are susceptible to bending and bulging.
Increasing wall thickness is one possible solution, but it is often not the most economical solution by itself.
A better design may combine PPH sheet with:
vertical ribs,
horizontal reinforcement,
external frames,
reduced reinforcement spacing,
tie rods.
DVS 2205-5 specifically addresses rectangular thermoplastic tanks, while tank design software can evaluate reinforcement configuration as part of the structural calculation.
Potentially, yes.
For rectangular tanks in particular, structural reinforcement can reduce unsupported wall span and therefore substantially affect the required wall design.
But this does not mean simply using the thinnest possible PPH sheet and adding arbitrary steel reinforcement.
The sheet thickness and reinforcement system should be designed together.
The calculation should consider:
PPH wall + reinforcement spacing + reinforcement stiffness + connection design + temperature expansion.
There is always a balance between:
material cost,
fabrication labour,
number of welds,
structural frame cost,
tank weight,
and long-term reliability.
The cheapest sheet thickness is not necessarily the lowest-cost tank.
“5,000 liters” is not enough information.
You still need dimensions, specific gravity and temperature.
The same PPH sheet thickness should not automatically be assumed suitable at 20°C and 80°C.
Long-term allowable material properties change with service conditions.
“Sulfuric acid tank” is incomplete.
The concentration and operating temperature are essential inputs.
A chemical tank may remain loaded continuously for many years.
Long-term creep performance must be considered.
A thick PPH sheet with poor welding can still produce an unreliable tank.
Wall material, welding rod, welding process and fabrication procedures should be compatible.
Tank penetrations can weaken the local structure.
Major nozzles and manholes should be included during the design phase.
Adding thickness generally increases structural capacity, but excessive thickness can increase:
material cost,
tank weight,
welding requirements,
fabrication difficulty,
and heat input during welding.
The goal is not to use the thickest sheet available.
The goal is to use the correct engineered thickness.
If you are requesting a PPH tank design or purchasing sheets for fabrication, prepare the following information.
Tank type: cylindrical / rectangular
Tank orientation: vertical / horizontal
Tank diameter or length × width
Tank height
Maximum liquid level
Required capacity
Chemical name
Concentration
Specific gravity
Normal operating temperature
Maximum design temperature
Atmospheric / pressure / vacuum
Continuous or intermittent operation
Required service life
Indoor or outdoor installation
Agitator or mixer
Major nozzle sizes
Reinforcement arrangement
Required design standard
Providing these parameters can dramatically improve the quality of the initial recommendation and quotation.
Correct thickness alone does not guarantee a reliable chemical tank.
The PPH sheet itself must also provide consistent material properties and fabrication quality.
Important characteristics include:
Large variations in sheet thickness can create unexpected weak areas and complicate structural fabrication.
Flat sheets simplify CNC cutting, butt welding and fabrication of large tank sections.
Chemical tanks contain many critical welded joints.
Stable material behaviour during hot-gas, extrusion or butt-fusion welding is therefore important.
For industrial projects, material certificates and batch consistency can help tank fabricators maintain project quality documentation.
The selected PPH grade must be evaluated against the intended operating medium and temperature.
Yubo Plastic's current PPH sheet range is customisable from 0.1 mm to 200 mm, and its β-PPH material is positioned for corrosion-resistant equipment including pickling and electrolytic tanks. Published typical properties include a density around 0.915 g/cm³ together with mechanical and chemical test data.
For a tank project, however, available sheet thickness should follow the engineering calculation—not the other way around.
There is no universal standard thickness based only on 1,000-liter capacity.
You need at least the tank dimensions, chemical, concentration, specific gravity, temperature and tank geometry before selecting a reliable wall thickness.
Possibly for some designs, but not for others.
A 10 mm sheet may be adequate for certain small, low-height or reinforced tanks but inadequate for a taller tank, higher-specific-gravity chemical or high-temperature application.
A structural calculation is required for the actual conditions.
Not automatically.
Wall thickness is only one part of tank design.
Welding quality, reinforcement, nozzles, supports, chemical compatibility, temperature, bottom construction and overall structural design are equally important.
Hydrostatic pressure increases with liquid depth.
The bottom section of a vertical tank therefore experiences greater liquid pressure than the upper section.
For large cylindrical tanks, this can justify using progressively thicker shell sections toward the bottom.
Yes.
Large fabricated cylindrical tanks may use several shell thicknesses to match the changing hydrostatic load.
The AGRU sulfuric-acid tank example used wall thicknesses ranging from 15 to 45 mm within a single tank design.
Yes.
Higher-specific-gravity liquids create greater structural loading.
Specific gravity should therefore be supplied before finalising tank wall thickness.
Yes.
Temperature influences the long-term mechanical behaviour and allowable design stress of thermoplastic materials.
A proper design therefore uses the actual service temperature instead of assuming room-temperature properties.
For engineered welded thermoplastic tanks, DVS 2205 is one widely used design framework.
DVS 2205-2 specifically covers vertical round non-pressurised thermoplastic tanks, while EN 12573 is another series used for welded static non-pressurised thermoplastic tanks.
The appropriate standard should be confirmed according to project and local requirements.
When choosing PPH sheet thickness for a chemical storage tank, do not start with sheet thickness.
Start with the operating conditions.
The correct sequence is:
Chemical + concentration → temperature → specific gravity → tank dimensions → geometry → service life → structural loads → calculation → PPH sheet thickness.
This approach avoids two common problems.
The first is under-design, where insufficient wall thickness can lead to excessive deformation, creep or premature structural problems.
The second is over-design, where unnecessarily thick PPH sheets increase material and fabrication cost without providing a proportional engineering benefit.
For large chemical tanks, the optimum solution may even use several PPH sheet thicknesses in different sections of the same tank.
If you are preparing a new chemical storage tank project, send your chemical, concentration, specific gravity, operating temperature, tank dimensions and required design life before requesting a final sheet thickness recommendation.
Yubo Plastic supplies PPH sheets in customised dimensions and a wide thickness range for chemical tank, pickling tank, electrolytic tank and other corrosion-resistant fabrication applications.
The objective should not be to buy the thickest PPH sheet.
It should be to select the right PPH sheet for an engineered, reliable and cost-effective chemical tank.
