Systematic asset expansion that consistently boosts cash flow and dividends: That’s what our six Conservative Holdings have in common.

Doing that effectively first means being able to identify promising opportunities for projects, and then locking in the business. But ultimate profitability also depends on being able to raise the needed capital to do the job. And that’s where our sweet six really separate themselves from the pack.

Enterprise Products Partners LP’s (NYSE: EPD) takeover bid for TEPPCO Partners LP (NYSE: TPP) will face a vote on October 23. Given the lack of any meaningful opposition to the merger agreement, approval looks certain.

The merger will create the largest energy infrastructure master limited partnership (MLP) in the US. More important, it’s set to be one of the most profitable as well, thanks to a strong asset base and management’s ability to raise capital at a reasonable cost.

This week Enterprise Products’ underwriters executed their full overallotment option, generating an additional $30 million in proceeds. The price of $28 is also encouraging, as it’s within a whisker of recent highs and demonstrates strong investor demand for the MLP’s equity.

That’s almost certainly in part because of the superb results of Enterprise Products’ $1.1 billion debt sale four days earlier. The MLP sold $500 million of 10-year notes at a spread of just 195 basis points to Treasuries.

That’s 500-plus points lower than the spread on an offering earlier this year. Even more impressive, $600 million of 30-year bonds went off at a spread of just 200 basis points.

Locking in that much debt at such low interest rates is infinitely more beneficial to the seller (Enterprise) than the mostly institutional buyers. But as MLP unitholders, it’s the seller’s interest we’re aligned with.

And this is fabulous news for Enterprise Products’ long-term cash flow and dividend growth. Shares have surged but are still a must-buy for those who don’t already own them. Enterprise Products Partners LP is a buy up to 30.

Kinder Morgan Energy Partners LP (NYSE: KMP) completed the previously announced purchase of the natural gas treating business of Crosstex Energy LP (NSDQ: XTEX) on Thursday.

The $266 million acquisition will immediately boost Kinder Morgan’s distributable cash flow and, by extension, help fund future dividend increases. The MLP is now the nation’s largest provider of contracted natural gas treating services.

At least equally impressive is the ease with which Kinder Morgan financed this deal. One reason is the successful sale of $400 million in debt maturing in 11.5 years at a 250 basis point spread to Treasuries, accompanied by the sale of $600 million in 30-year notes at a spread of just 240 basis points.

Fetching a lower spread for the longer-dated paper is unusual, to say the least. It’s still more clear proof of the MLP’s ability to access cheap capital to spur growth. Kinder Morgan Energy Partners is also a must-buy for those who don’t already own it, up to 55.

Magellan Midstream Partners LP (NYSE: MMP) took a giant leap toward potentially reducing its already low cost of capital, as unitholders approved its merger with general partner Magellan Midstream Holdings.

The transaction will initially dilute the MLP’s ownership base by 4 percent. It will also, however, lift unitholders’ share of cash flow from the assets by 13 percentage points, with a commensurate upward push in cash flow and distributions.

Revenue from the MLP’s refined petroleum products’ transportation network is extremely reliable because of wide reach and high customer quality. The pipeline network now accesses 40 percent of US refining capacity and features 85 terminals with 60 million barrels of storage capacity.

And management states it has some $250 million in organic projects–asset expansions with locked-in customers–it will complete this year and $500 million more that can come on the next couple of years.

Magellan Midstream Partners’ 10-year debt is currently trading with a yield-to-maturity of just 5.12 percent. That’s less than 200 basis points above the yield on equivalent Treasuries and a good sign that management will have no troubles getting the low cost capital it needs to complete its project backlog. Buy Magellan Midstream Partners LP if you haven’t already up to 40.

Spectra Energy Partners LP (NYSE: SEP) and its parent Spectra Energy (NYSE: SE) hosted a conference call in mid-September that focused on part on management’s strategy of using the MLP as a way to maximize cash flows from secure assets.

That’s a strategy we’re certain to see more of in coming years, as Spectra Energy focused more deeply on fee-based assets like pipelines and moves away from commodity-based operations.

Spectra Energy has already “dropped down” valuable assets to the MLP, including the recently purchased NOARK pipeline system connecting the prolific Fayetteville Shale region with major markets. And Spectra’s blue chip balance sheet is a resource for the MLP that can’t be overstated.

If there is a knock on Spectra Energy Partners now it’s that the price has risen above our buy target of $24 a share. If you haven’t yet bought in, be patient for a dip to our target. But this is a solid MLP with great prospects for growing distributions, which it’s done every quarter since inception.

Genesis Energy LP (NYSE: GEL) and Sunoco Logistics Partners LP (NYSE: SXL) have both rallied from our initial recommendations. Each, however, has more than justified their moves by posting solid results, matching the solid showing of the other four Conservative Holdings highlighted above.

Of the pair, only Sunoco Logistics has reported a significant business development in the past month. Specifically, the MLP completed the acquisition of Excel Pipeline LLC, the owner of a 52-mile pipeline delivering crude oil to the Gary-Williams refinery in Wynnewood, Okla.

Both MLPs, however, continue to benefit from growing positives in North American oil industry activity, fueled in part by black gold’s recovery to the $70 per barrel range. Both operate infrastructure that will remain absolutely essential to the American economy as long as oil is used in any capacity, which should be a very long time to come. And both continue to face few if any challenges raising capital to expand their cash flows and distributions.