High-rise buildings—think 30+ story residential towers or skyscrapers—rely on stainless steel pipes for everything from water supply to HVAC systems. But these pipes face two big threats: earthquakes and long-term leaks. A 2019 earthquake in Japan showed just how risky bad pipe connections can be: in a 42-story apartment building, traditional welded stainless steel pipes cracked at the joints, causing water damage to 20+ lower-floor units. And leaks from old threaded connections? They’re the #1 cause of mold growth in high-rises, costing landlords $5.000+ per repair on average.
That’s where double crimp connection technology comes in. Unlike welding (which weakens steel at high heat) or threaded connections (which loosen over time), double crimping uses two circular presses to lock stainless steel pipes to fittings—creating a tight, flexible joint. But does it hold up in earthquakes? And can it stay leak-free for 20+ years (the expected lifespan of a high-rise’s plumbing system)?
This article breaks down the seismic test results and long-term sealing data for double crimp connections, plus real-world examples from high-rises around the world. By the end, you’ll know why more builders are ditching welding for this simpler, more reliable pipe connection method.
Why Double Crimp Connections Beat Traditional Methods in High-Rises
First, let’s clear up why double crimping is better for tall buildings. High-rise pipes face unique stress: they’re longer (so more weight to support), they vibrate from wind or elevator movement, and in seismic zones, the building itself can shift 10–20cm during an earthquake. Traditional connections struggle with this—here’s how double crimping solves the problem:
Connection Type | Seismic Flexibility | Risk of Leaks (After 10 Years) | Installation Time (Per Joint) | Cost (Per Joint) |
Double Crimp | Bends up to 5° without leaking | 2% | 2 minutes | 8– 12 |
Welded | Brittle—cracks at >1° bend | 15% | 10 minutes | 15– 20 |
Threaded | Loosens at >2° bend | 30% | 5 minutes | 5– 8 |
The key advantage of double crimping is its flexibility with tightness. The two crimps (one on the pipe, one on the fitting) create a seal that can bend slightly when the building shifts—like a rubber band that stretches without breaking. Welded joints are rigid; they crack instead of bending. Threaded joints loosen over time, especially with vibration—think of a jar lid that works loose after being shaken.
A plumber who installed double crimp pipes in a 38-story tower in Los Angeles put it best: “With welding, I’d worry about a earthquake cracking the joint. With double crimp? I’ve seen the test videos—those joints bend and still don’t leak. It’s a no-brainer for high-rises.”
Seismic Test Results: How Double Crimp Connections Hold Up to Earthquakes
To prove its seismic strength, the American Society of Testing and Materials (ASTM) ran a series of tests on 304 stainless steel pipes (50mm diameter, common in high-rise water systems) with double crimp connections. They simulated earthquake conditions using a shake table that mimicked the 2011 Tohoku earthquake (magnitude 9.0)—one of the strongest on record. Here’s what they found:
1. Bend Test (Simulating Building Shift)
The test team bent the pipe joints 1° at a time, up to 5°, while running water through the pipes at 80 psi (standard high-rise water pressure). Results:
Double crimp connections: No leaks at up to 5° of bend. Even at 6°, only 1 out of 20 joints leaked (and it was a slow drip, not a gush).
Welded connections: 50% cracked at 2° bend; 100% leaked at 3°.
Threaded connections: 30% loosened and leaked at 2°; 80% leaked at 3°.
Why the difference? Double crimp joints use a rubber O-ring inside the fitting, which stays tight even when the pipe bends. Welded joints have no give—they’re like a rigid stick that snaps when you bend it too far.
2. Vibration Test (Simulating Long-Term Building Movement)
High-rises vibrate constantly from wind, elevators, and foot traffic—this can loosen threaded joints over time. The ASTM team vibrated pipes at 5 Hz (similar to elevator vibration) for 1.000 hours (about 6 weeks of non-stop movement). Results:
Double crimp connections: 0 leaks. The crimps stayed tight, and the O-ring showed no wear.
Threaded connections: 40% leaked after 500 hours; 70% leaked after 1.000 hours.
Welded connections: 5% leaked after 1.000 hours (due to small cracks from vibration).
A seismic engineer on the test team said: “Double crimp connections don’t just survive big earthquakes—they handle the small, constant vibrations that break down other joints over time. That’s crucial for high-rises, which are always moving.”
Long-Term Sealing Evaluation: 15 Years of Leak-Free Performance
Seismic strength is great, but a pipe connection needs to stay leak-free for decades. To test this, a research team in Germany tracked 500 double crimp stainless steel pipe joints in 10 high-rises (built between 2008 and 2010) for 15 years. Here’s what they found:
1. Leak Rate
Only 10 out of 500 joints (2%) leaked over 15 years. Most leaks were small (a few drops per day) and caused by improper installation (e.g., the crimp tool wasn’t calibrated correctly), not the technology itself. For comparison, a similar study on welded joints found a 15% leak rate after 15 years.
2. O-Ring Durability
The rubber O-rings inside the double crimp fittings showed minimal wear. Even in hot water pipes (up to 60°C), the O-rings retained their elasticity—no hardening or cracking. The team attributed this to the use of EPDM rubber (a heat-resistant material) in most double crimp fittings.
3. Corrosion Resistance
Stainless steel pipes and double crimp fittings showed no signs of corrosion, even in buildings near the coast (where salt air can rust metal). The crimped areas didn’t trap water or dirt—unlike threaded joints, which have small gaps where corrosion can start.
One of the buildings in the study was a 32-story apartment tower in Hamburg. The building manager said: “In 15 years, we’ve only had to repair two pipe joints—both from bad installation. The double crimp system has been maintenance-free. I wish we’d used it for all our buildings.”
Real-World Case: A 45-Story Tower in San Francisco
San Francisco is a high-seismic zone, so when builders broke ground on a 45-story residential tower in 2018. they chose double crimp connections for all stainless steel water pipes. Here’s how it worked:
Installation: A team of 5 plumbers installed 2.000+ double crimp joints in 8 weeks. They used a battery-powered crimp tool (calibrated daily) to ensure consistent pressure.
Seismic Prep: The pipes were attached to flexible hangers that let them move with the building during an earthquake.
5-Year Follow-Up: As of 2023. there have been 0 leaks. During a 2022 magnitude 4.5 earthquake, the building shifted about 5cm, but the pipe joints showed no damage.
The project engineer said: “We saved 30% on installation time compared to welding. And we don’t have to worry about future leaks or earthquake damage. It’s been a huge success.”
How to Ensure Proper Double Crimp Installation (Avoid Common Mistakes)
Double crimp connections work well—if they’re installed correctly. Here are the 3 most common mistakes and how to avoid them:
1. Using an Uncalibrated Crimp Tool
If the tool doesn’t apply enough pressure, the joint will leak. Calibrate the tool every 500 crimps (or weekly, whichever comes first) using a test gauge. A plumber in Chicago once used an uncalibrated tool—100 joints leaked within 6 months, costing $20.000 to fix.
2. Cutting the Pipe Crookedly
A uneven pipe end won’t fit properly into the fitting. Use a pipe cutter (not a hacksaw) to get a straight, clean cut. Deburr the pipe after cutting to remove sharp edges that can damage the O-ring.
3. Not Inserting the Pipe Fully
The pipe must be pushed all the way into the fitting before crimping. Most fittings have a mark—line up the pipe with the mark to ensure full insertion. A half-inserted pipe will crimp loosely and leak.
Conclusion
For high-rise buildings, double crimp connection technology is the best choice for stainless steel pipes. It outperforms welding and threading in seismic flexibility, long-term sealing, and installation speed. The test data speaks for itself: 2% leak rate after 15 years, no cracks at up to 5° of bend, and minimal maintenance.
Builders in seismic zones (like San Francisco, Tokyo, or Los Angeles) should prioritize double crimp connections—it’s a simple way to protect against earthquake damage and costly leaks. Even in non-seismic zones, the long-term durability of double crimp joints makes it a smart investment.
At the end of the day, a high-rise’s plumbing system is only as good as its connections. Double crimp technology ensures those connections stay strong and leak-free—for decades. It’s not just a better way to connect pipes; it’s a way to build safer, more reliable high-rises.
