PEX Pipe vs Steel Pipe

For both residential and commercial plumbing applications, choosing the optimal pipe material is crucial for balancing cost, performance, and longevity. Two popular options are crosslinked polyethylene (PEX) plastic pipes and traditional steel pipes. As a veteran plumber and contractor, I've installed miles of both PEX and steel piping. In this guide, I'll compare PEX vs steel pipe across factors like durability, corrosion resistance, installation challenges, freeze resistance, and long-term ownership cost. My goal is to provide an unbiased expert perspective to help determine which material may be best suited for your unique plumbing application needs.

 

PEX Pipe Overview

First, a quick background on PEX tubing. PEX stands for cross-linked polyethylene, a specialized plastic piping commonly used for hot and cold potable water delivery as well as radiant floor heating systems. Key traits include:

- Flexible plastic tubing instead of rigid pipes. Withstands freezing and resists corrosion.

- Simple push-fit, compression or crimp connections. No gluing or torching is needed.

- Easy for DIY homeowners to install. Can bend around corners, reducing joints.

- Common types are PEX-A, PEX-B, and PEX-C with varying temperature/pressure ratings.

- Sizes from 1/4” to 2” for residential applications. 1/2” to 1” is the most common.

- Expect a 50+ year lifespan with proper installation. Maintenance-free.

 

With its flexible tubing, simple joining, and corrosion resistance, PEX has gained popularity as an alternative to traditional metal piping. But how does it truly compare to steel?

Steel Pipe Overview

Steel has been used for decades in commercial and residential plumbing applications. Its characteristics include:

- Rigid metal pipes. Various wall thicknesses from light 1/2” to heavy 1”+ commercial sizes.

- Threaded seal fittings must be threaded, Teflon tape, and wrenched tight. Labor-intensive joints.

- Robust material with excellent pressure ratings. Withstands abuse.

- Corrosion potential leading to leaks, though galvanized and stainless steel resists corrosion.

- Sizes from 1/4” to many inches. 1/2” to 1” typical for residential.

- Can last more than 70 years in ideal conditions. Outlasts buildings.

 

With its strength but demanding connections, steel remains popular in commercial plumbing, but homeowners should weigh tradeoffs versus simpler PEX.

Cost Comparison: PEX vs Steel

An obvious factor in any pipe selection is the cost, of both materials and labor:

PEX:
- Inexpensive polyethylene tubing, often under $1 per foot.
- Low-cost fittings like crimp rings for connections. Complete joints can be under $5.
- No specialty tools are required. Installs with basic crimper, cutter, and expander.
- Fast to install. Easily cut and quickly joined.
- DIY-friendly installation further reduces labor costs.

Steel:
- Low carbon steel pipes alone are $1-$5 per foot, based on diameter and metals market.
- Fittings, nipples, and couplings substantially add to material costs.
- Joint compound, Teflon tape, and wrenches required for installations.
- Slow to thread, de-burr, clean, and assemble threaded joints.
- Installation requires skilled trades familiar with threading and joining steel pipe.

Overall, PEX piping systems can cost 50% or less than comparable steel. But for larger diameter low-pressure commercial plumbing where steel prices per foot drop, the material cost difference narrows. However, PEX retains significant labor savings. While heavy steel is ideal for some uses, PEX merits consideration for its affordability.

 

Performance Comparison: PEX vs Steel

Beyond raw costs, performance factors also impact material selection:

PEX:
- Flexible tubing simplifies routing through framing and joists vs steel.
- No fire risk. Steel threading and jointer compound involve open flames.
- Can easily be retrofitted into existing piping systems.
- Quieter water flow than rigid steel. Minimizes noise complaints.
- Maximum 200°F temperature rating. Suitable for hot water delivery.
- Can withstand pressures up to 200psi @ 73°F. Higher burst pressure when hot.

Steel:
- Rigid pipe with threaded fittings needs planning for turns and routing.
- Leak-proof when correctly sealed and supported.
- Withstands over 300°F. Used for steam lines and heating.
- Extremely high-pressure ratings beyond 300psi for schedule 40 steel.
- Thick steel deadens sound and reduces water hammer vibrations.

 

PEX provides easier routing and installation for DIYers, while steel suits high-temperature/pressure commercial applications. Needs determine ideal performance traits.

Installation Comparison: PEX vs Steel

Ease and speed of installation also impact material evaluation:

PEX:
- No special skills or tools are needed. Cut tubing and connect fittings.
- Fast installation with simple push-fit or crimp connections.
- Flexibility allows routing through framing with minimal cutting.
- Fewer connections than steel due to bending around corners.
- Expanding tools form secure, reliable joints. No threading is needed.

Steel:
- Piping skills needed for precise cutting, deburring, threading, and assembly.
- Slow, methodical preparation is required before assembling threaded joints.
- Steel must be annealed with torches for bending. Pipes otherwise stay rigid.
- Threaded connections must be perfectly straight and aligned to prevent leaks.
- Joint compound and Teflon tape seal threads but make a mess requiring cleanup.

For novice DIYers or anyone valuing simple installation, PEX provides a much shallower learning curve. Flexible tubing and push-fittings enable fast connections without messy compounds or threading equipment. PEX installs in a fraction of the time.

 

However, skilled steel fabrication allows extremely robust commercial plumbing. Leak-proof threaded connections can outlast generations if properly assembled. High temperatures and pressures pose no concern. This dependability makes steel ideal for harsh industrial conditions.

 

Maintenance Comparison: PEX vs Steel

Ongoing maintenance requirements vary by material:

PEX:
- No maintenance needed. Does not corrode or accumulate scale buildup over time.
- Leaks requiring repairs are unlikely. Lasts 50+ years without issues.
- Flexible tubing is highly freeze-resistant. Withstands freeze-thaw cycles.

Steel:
- Corrosion potential leading to eventual pinhole leaks, depending on water chemistry. Galvanized and stainless steel resist corrosion far better than basic carbon steel and cast iron pipes if installed properly.
- Periodic repainting of buried steel lines needed to fight corrosion.
- Can last extremely long - over 70 years expected service life.
- Rigid pipes burst if water freezes. Insulation and heat tracing are needed in cold climates.

If installed correctly using manufacturer guidelines, PEX needs no ongoing maintenance except standard fixture/valve replacements over decades of service. Steel must be selected, installed, and maintained according to standards to maximize corrosion resistance based on environmental conditions like soil pH, water pH, and temperature. But properly maintained steel can serve dependably for lifetimes.

 

Ideal Applications: PEX vs Steel

Based on the factors above, ideal applications align as:

PEX:
- Hot and cold residential potable water plumbing lines
- In-floor radiant heating systems
- DIY home plumbing
- Repiping old steel plumbing inaccessible for repairs
- Trench burial with fewer connections
- Challenging routing situations through framing
- Corrosive water conditions

Steel:
- Commercial hot and cold water plumbing
- High-pressure fluid delivery lines
- Plumbing systems near vibrations needing sound damping
- Straight routing patterns accessible for later maintenance
- Heating, cooling, and steam lines where moderate copper temperatures insufficient
- Proven material for both underground and exposed installations
- High-rise occupied buildings where service lifespans sought

By matching strengths and tolerable weaknesses to needs and priorities, either material can excel. The key is analyzing factors like temperature, pressure, installation skill, maintenance access, and building lifespan to guide ideal pairings.

 

In summary, while flexible PEX expedites installation for limited space routing, steel provides sheer dependability for the most demanding plumbing applications. There is no universal "best" choice between PEX and steel. Carefully weighing project requirements against material capabilities and limitations guide proper selection for long-lasting results. With mindful specification and quality installation, both PEX and steel can provide generations of reliable service by living up to their intended applications. I hope this detailed plumbing material comparison assists in making the most informed possible decision when planning upcoming residential or commercial plumbing projects. Please reach out with any other questions!